9tM

QlnlUge of IGtberal ArtH

Htbrarg

jAliofNV\ss>Be\eT\ Stevens to the.

THE

CHEMICAL HISTORY OF A CANDLE.

^

COURSE OF SIX LECTURES

CHEMICAL HISTORY OF A CANDLE

TO M-niCU IS ADDED

A LECTURE ON PLATINUM.

BY

MICHAEL FARADAY, D.C.L., F.R.S.,

FULLERIAN PKOFESSOE OP CHEMISTBY, EOYAl, INSTITtXTION ; FOBEIQN

ASSOCIATE OF THE ACADEMY OF SCIENCES, ETC.

Delivered be/ore a Jttvenile Axjditoey at the Eoyal Institution of

Gbeat Beitain during the Christmas Holidays of 1S60-1.

EDITED BY WILLIAM CROOKES, F.C.S.

WITH NUMEROUS ILLUSTRATIONS.

NEW YORK:HARPER & BROTHERS, PUBLISHERS,

FBANKMN SQfTABK.

i-f-^ of riiss Helt-rv SVevf VIS

March a 19^V

PREFACE.

Feom the primitive pine torch to the paraf-

fine candle, how "wide an interval! between

them how vast a contrast ! The means adopt-

ed by man to illuminate his home at night

stamp at once his position in the scale of civili-

zation. The fluid bitumen of the far East,

blazing in rude vessels of baked earth; the

Etruscan lamp, exquisite in form, yet ill adapt-

ed to its office; the whale, seal, or bear fat,

filling the hut of the Esquimaux or Lap with

odor rather than light ; the huge wax candle

on the glittering altar ; the range of gas-lamps

in our streets, all have their stories to tell. All,

if they could speak (and after their own man-

ner they can), might warm our hearts in telling

how they have ministered to man's comfort,

love of home, toil, and devotion.

Surely, among the millions of fire-worshipers

and fire-users who have passed away in earlier

vi TREFACE.

ages, some have pondered over the mystery of

fire;perhaps some clear minds have guessed

shrewdly near the truth. Think of the time

man has lived in hopeless ignorance; think

that only during a period which might be

spanned by the life of one man has the truth

been known

!

Atom by atom, link by link, has the reason-

ing chain been forged. Some links too quickly

and too slightly made have given way, and

been replaced by better work; but now the

great phenomena are known, the outline is cor-

rectly and firmly drawn, cunning artists are

filling in the rest, and the child who masters

these Lectures knows more of fire than Aris-

totle.

The candle itself is now made to light up the

dark places of nature ; the blowpipe and the

prism are adding to our knowledge of the

earth's crust, but the torch must come first.

Among the readers of this book, some few

may devote themselves to increasing the stores

of knowledge : the Lamp of Science must burn.

" Alere flammam." W. C.

CONTENTS.

LECTURE I.PAGE

A candle: the flame—ITS SOURCES—STRUCTURE

—

MOBILITY—BRIGHTNESS 9

LECTURE II.

BRIGHTNESS OF THE FLAME. — AIR NECESSARY FOR

COMBUSTION.—PRODUCTION OF WATER 39

LECTURE III.

PRODUCTS : WATER FROM THE COMBUSTION.— NATURE

OF WATER.—A COMPOUND.—HYDROGEN 64

LECTURE IV.

HYDROGEN IN THE CANDLE. BURNS INTO WATER. —THE OTHER PART OF WATER.—OXYGEN 94

LECTURE V.

OXYGEN PRESENT IN THE AIR.— NATURE OF THE AT-

MOSPHERE. ITS PROPERTIES. OTHER PRODUCTS

FROM THE CANDLE.—CARBONIC ACID.—ITS PROPER-

TIES 121

VIU CONTENTS.

LECTURE VI.PAGE

CARBON OR CHARCOAL. — COAL - GAS. — RESPIRATION

AND ITS ANALOGY TO THE BURNING OF A CANDLE.

—CONCLUSION 153

LECTURE ON PLATINUM 185

NOTES 219

LECTURES

CHEMICAL HISTORY OF A CANDLE.

LECTUEE I.

A CANDLE: THE FLAME— ITS SOURCES—STRUCTURE—MOBILITY—BRIGHTNESS.

I PURPOSE, in return for the honor you do

us by coming to see what are our proceedings

here, to bring before you, in the course of

these lectures, the Chemical History of a Can-

dle. I have taken this subject on a former oc-

casion, and, were it left to my own will, I

should prefer to repeat it almost every year,

so abundant is the interest that attaches itself

to the subject, so wonderful are the varieties

of outlet which it offers into the various de-

partments of philosophy. There is not a ]aw

under which any part of this universe is gov-

erned which does not come into play and is'

10 PRIMITIVE CANDLES.

touched upon in these phenomena. There is

no better, there is no more open door by which

you can enter into the study of natural phi-

losophy than by considering the physical phe-

nomena of a candle. I trust, therefore, I shall

not disappoint you in choosing this for my sub-

ject rather than any newer topic, which could

not be better, were it even so good.

And, before proceeding, let me say this also

:

that, though our subject be so great, and our

intention that of treating it honestly, seriously,

and philosophically, yet I mean to pass away

from all those who are seniors among us. I

claim the privilege of speaking to juveniles as

a juvenile myself. I have done so on former

occasions, and, if you please, I shall do so again.

And, though I stand here with the knowledge

of having the words I utter given to the world,

yet that shall not deter me from speaking in

the same familiar way to those whom I esteem

nearest to me on this occasion.

And now, my boys and girls, I must first tell

you of what candles are made. Some are great

curiosities. I have here some bits of timber,

branches of trees particularly famous for their

CANDLE-WOOD. Hburning. And here you see a piece of that

f very curious substance, taken out of some of

the bogs in Ireland, called candle-wood; a hard,

strong, excellent wood, evidently fitted for good

work as a register of force, and yet, withal,

burning so well that where it is found they

make splinters of it, and torches, since it burns

like a candle, and gives a very good light in-

deed. And in this wood we have one of the

most beautiful illustrations of the general na-

ture of a candle that I can possibly give. Thefuel provided, the means of bringing that fuel

to the place of chemical action, the regular and

gradual supply of air to that place of action

—

heat and light—all produced by a little piece

of wood of this kind, forming, in fact, a natu-

ral candle.

But we must speak of candles as they are in

commerce. Here are a couple of candles com-

monly called dips. They are made of lengths

of cotton cut off, hung up by a loop, dipped

into melted tallow, taken out again and cooled,

then redipped, until there is an accumulation

of tallow round the cotton. In order that youmay have an idea of the various characters of

12

these candles, you see these which I hold in

my hand—they are very small and very curi-

ous. They are, or were, the candles used by

the miners in coal mines. In olden times the

miner had to find his own candles, and it was

supposed that a small candle would not so soon

set fire to the fire-damp in the coal mines as a

large one ; and for that reason, as well as for

economy's sake, he had candles made of this

sort—20, 30, 40, or 60 to the pound. " They

have been replaced since then by the steel-mill,

and then by the Davy lamp, and other safety-

lamps of various kinds. I have here a candle

that was taken out of the Royal Oeorge^i^) it

is said, by Colonel Pasley. It has been sunk

in the sea for many years, subject to the action

of salt water. It shows you how well candles

may be preserved; for, though it is cracked

about and broken a good deal, yet when light-

ed it goes on burning regularly, and the tallow

resumes its natural condition as soon as it is

fused.

Mr. Field, of Lambeth, has supplied me

abundantly with beautiful illustrations of the

candle and its materials ; I shall therefore now

STEARIN CANDLES. 13

refer to them. And, first, there is the suet

—

the fat of the ox—Kussian tallow, I believe,

employed in the manufacture of these dips,

which Gay-Lussac, or some one who intrusted

him with his knowledge, converted into that

beautiful substance, stearin, which you see ly-

ing beside it. A candle, you know, is not now

a greasy thing like an ordinary tallow candle,

but a clean thing, and you may almost scrape

off and pulverize the drops which fall from it

without soiling any thing. This is the process

be adopted :(^) The fat or tallow is first boiled

with quick-lime, and made into a soap, and then

the soap is decomposed by sulphuric acid, which

takes away the lime, and leaves the fat rear-

ranged as stearic acid, while a quantity of gly-

cerin is produced at the same time. Glycerin

—absolutely a sugar, or a substance similar to

sugar—comes out of the tallow in this chemical

change. The oil is then pressed out of it; and

you see here this series of pressed cakes, show-

ing how beautifully the impurities are carried

out by the oily part as the pressure goes on in-

creasing, and at last you have left that sub-

stance, which is melted, and cast into candles

14 PARAFFINE CANDLES.

as here represented. The candle I have in myhand is a stearin candle, made of stearin from

tallow in the way I have told you. Then here

is a sperm candle, which comes from the puri-

fied oil of the spermaceti whale. Here, also, are

yellow bees'-wax and refined bees'-wax, from

which candles are made. Here, too, is that

curious substance called paraffine, and some

parafiine candles, made of parafiine obtained

from the bogs of Ireland. I have here also a

substance brought from Japan since we have

forced an entrance into that out-of-the-way

place—a sort of wax which a kind friend has

sent me, and which forms a new material for

the manufacture of candles.

And how are these candles made ? I have

told you about dips, and I will show you how

moulds are made. Let us imagine any of these

candles to be made of materials which can be

cast. " Cast !" you s^j. " Why, a candle is a

thing that melts, and surely if you can melt it

you can cast it." Not so. It is wonderful, in

the progress of manufacture, and in the consid-

eration of the means best fitted to produce the

required result, how things turn up which one

TALLOW CANDLES. 15

would not expect beforehand. Candles can

not always be cast. A wax candle can never

be cast. It is made by a particular process

which I can illustrate in a minute or two, but

I must not spend much time on it. Wax is a

thing which, burning so "well, and melting so

easily in a candle, can not be cast. However,

let us take a material that can be cast. Here

is a frame, with a number of moulds fastened in

it. The first thing to be done is to put a wick

through them. Here is one—a plaited wick,

which does not require snuj3ing(^)—supported

by a little wire. It goes to the bottom, where

it is pegged in ; the little peg holding the cot-

ton tight, and stopping the aperture so that

nothing fluid shall run out. At the upper part

there is a little bar placed across, which stretch-

es the cotton and holds it in the mould. The

tallow is then melted, and the moulds are filled.

After a certain time, when the moulds are cool,

the excess of tallow is poured off at one corner,

and then cleaned off altogether, and the ends

of the wick cut away. The candles alone then

remain in the mould, and you have only to

upset them, as I am doing, when out they tum-

16 WAX CANDLES.

ble, for the candles are made in the form of

cones, being narrower at the top than at the

bottom ; so that, what with their form and their

own shrinking, they only need a little shaking

and out they fall. In the same way are made

these candles of stearin and of paraffine. It is

a curious thing to see how wax candles are

made. A lot of cottons are hung upon frames,

as you see here, and covered with metal tags at

the ends to keep the wax from covering the

cotton in those places. These are carried to a

heater, where the wax is melted. As you see,

the frames can turn round ; and, as they turn,

a man takes a vessel of wax and pours it first

down one, and then the next, and the next,

and so on. When he has gone once round, if

it is sufficiently cool, he gives the first a second

coat, and so on until they are all of the required

thickness. When they have been thus clothed,

or fed, or made up to that thickness, they are

taken off and placed elsewhere. I have here,

by the kindness of Mr. Field, several specimens

of these candles. Here is one only half finish-

ed. They are then taken down and well roll-

ed upon a fine stone slab, and the conical top

OliNAMENTAL CANDLES. 17

is moulded by properly shaped tubes, and tlie

bottoms cut off and trimmed. This is done so

beautifully that they can make candles in this

way weighing exactly four or six to the pound,

or any number they please.

"We must not, however, take up more time

about the mere manufacture, but go a little

farther into the matter. I have not 3^et refer-

red you to luxuries in candles (for there is such

a thing as luxury in candles). See how beau-

tifully these are colored;you see here mauve,

Magenta, and all the chemical colors recently

introduced, applied to candles. You observe,

also, different forms employed. Ilere is a

fluted pillar most beautifully shaped; and I

have also here some candles sent me by Mr.

Pearsall, which are ornamented with designs

upon them, so that, as they burn, you have, as

it were, a glowing sun above, and a bouquet of

flowers beneath. All, however, that is fine and

beautiful is not useful. These fluted candles,

pretty as they are, are bad candles ; they are

bad because of their external shape. Never-

theless, I show you these specimens, sent to mefrom kind friends on all sides, that you may

B

18 MODE OF BURNING.

see what is done and what may be done in thi3

or that direction ; although, as I have said,

when we come to these refinements, we are

obliged to sacrifice a little in utility.

ISTow as to the light of the candle. "We will

light one or two, and set them at work in the

performance of their proper functions. You

observe a candle is a very different thing from

a lamp. With a lamp you take a little oil, fill

your vessel, put in a little moss or some cotton

prepared by artificial means, and then light the

top of the wick. When the flame runs down

the cotton to the oil, it gets extinguished, but

it goes on burning in the part above. Kow I

have no doubt you will ask how it is that the

oil which will not burn of itself gets up to the

top of the cotton, where it will burn. Weshall presently examine that; but there is a

much more wonderful thing about the burning

of a candle than this. You have here a solid

substance with no vessel to contain it; and

how is it that this solid substance can get up

to the place where the flame is? How is it

that this solid gets there, it not being a fluid?

or, when it is made a fluid, then how is it that

THE CUP. 19

it keeps together ? This is a wonderful thing

about a candle.

We have here a good deal of wind, which

will help us in some of our illustrations, but

tease us in others ; for the sake, therefore, of a

little regularity, and to simplify the matter, I

shall make a quiet flame, for who can study a

subject when there are difficulties in the way

not belonging to it? Here is a clever inven-

tion of some costermonger or street-stander in

the market-place for the shading of their can-

dles on Saturday nights, when they are selling

their greens, or potatoes, or fi^h. I have very

often admired it. They put a lamp-glass round

the candle, supported on a kind of gallery,

which clasps it, and it can be slipped up and

down as required. By the use of this lamp-

glass, employed in the same way, you have a

steady flame, which you can look at, and care-

fully examine, as I hope you will do, at home.

You see then, in the first instance, that a

beautiful cup is formed. As the air comes to

the candle, it moves upward by the force of the

current which the heat of the candle produces,

and it so cools all the sides of the wax, tallow,

20 CANDLES OF IRREGULAR SHAPE.

or fuel as to keep the edge much cooler than

the part within ; the part within melts by the

flame that runs down the wick as far as it can

go before it is extinguished, but the part on

the outside does not melt. If I made a current

in one direction, my cup would be lop-sided,

and the fluid would consequently run over;

for the same force of gravity which holds worlds

together holds this fluid in a horizontal position,

and if the cup be not horizontal, of course the

fluid will run away in guttering. You see,

therefore, that the cup is formed by this beau-

tifully regular ascending current of air playing

upon all sides, which keeps the exterior of the

candle cool. Ko fuel would serve for a candle

which has not the property of giving this cup,

except such fuel as the Irish bog-wood, where

the material itself is like a sponge and holds its

own fuel. You see now why you would have

had such a bad result if you were to burn these

beautiful candles that I have shown you, which

are irregular, intermittent in their shape, and

can not, therefore, have that nicely-formed edge

to the cup which is the great beauty in a can-

dle. I hope you will now see that the perfec-

CAUSE OF GUTTERING. 21

tien of a process—that is, its utility—is the bet-

ter point of beauty about it. It is not the best

looking thing, but the best acting thing, which

is the most advantageous to us. This good-

looking candle is a bad-burning one. There

will be a guttering round about it because of

the irregularity of the stream of air and the bad-

ness of the cup which is formed thereby. You

may see some pretty examples (and I trust you

will notice these instances) of the action of the

ascending current when you have a little gutter

run down the side of a candle, making it thick-

er there than it is elsewhere. As the candle

goes on burning, that keeps its place and forms

a little pillar sticking up by the side, because,

as it rises higher above the rest of the wax or

fuel, the air gets better round it, and it is more

cooled and better able to resist the action of the

heat at a little distance. ISTow the greatest mis-

takes and faults with regard to candles, as in

many other things, often bring with them in-

struction which we should not receive if they

had not occurred. We come here to be philos-

ophers, and I hope you will always remember

that whenever a result happens, especially if it

22 RISE OF FLUID IN THE WICK.

be new, you should say, ^' What is the cause?

Why does it occur?" and you will, in the

course of time, find out the reason.

Then there is another point about these can-

dles which will answer a question—that is, as

to the way in which this fluid gets out of the

cup, up the wick, and into the place of com-

bustion. You know that the flames on these

burning wicks in candles made of bees'-wax,

stearin, or spermaceti, do not run down to the

wax or other matter, and melt it all away, but

keep to their own right place. They are fenced

off from the fluid below, and do not encroach

on the cup at the sides. I can not imagine a

more beautiful example than the condition of

adjustment under which a candle makes one

part subserve to the other to the very end of

its action. A combustible thing like that, burn-

ing away gradually, never being intruded upon

by the flame, is a very beautiful sight, especial-

ly when you come to learn what a vigorous

thing flame is— what power it has of destroy-

ing the wax itself when it gets hold of it, and

of disturbing its proper form if it come only too

near.

CAPILLARY ATTRACTION. 23

But how does tlie flame get hold of the fael ?

There is a beautiful point about that

—

capillary

attraction. {^) "Capillary attraction!" you say

—" the attraction of hairs." Well, never mind

the name ; it was given in old times, before we

had a good understanding of what the real

power was. It is by what is called capillary

attraction that the fuel is conveyed to the part

where combustion goes on, and is deposited

there, not in a careless way, but very beauti-

fully in the very midst of the centre of action,

which takes place around it. Now I am going

to give you one or two instances of capillary

attraction. It is that kind of action or attrac-

tion which makes two things that do not dis-

solve in each other still hold together. Whenyou wash your hands, you wet them thorough-

ly;you take a little soap to make the adhesion

better, and you find your hand remains wet.

This is by that kind of attraction of which I

am about to speak. And, what is more, if your

hands are not soiled (as they almost always are

by the usages of life), if you put your finger

into a little warm water, the water will creep a

little way np the finger, though ^you may not

24 CAPILLARY ACTION.

stop to examine it. I have here a substance

whicli is rather porous— a column of salt

—

and I -will pour into the plate at the bottom,

not water, as it appears, but a saturated solution

of salt which can not absorb more, so that the

action which you see will not be due to its

dissolving any thing. We may consider the

plate to be the candle, and the salt the wick,

and this solution the melted tallow. (I have

colored the fluid, that you may see the action

better.) You observe that, now I pour in the

fluid, it rises and gradually creeps up the salt

higher and higher ; and provided the column

does not tumble over, it will go to the top. If

Fig. 1.

this blue solution were combustible, and we

were to place a wick at the top of the salt, it

would burn as it entered into the wick. It is

ACTION OF THE SIPHON. 25

a most curious thing to see this kind of action

taking place, and to observe how singular some

of the circumstances are about it. When you

wash your hands, you take a towel to wipe off

the water ; and it is by that kind of wetting, or

that kind of attraction which makes the towel

become wet with water, that the wick is made

wet with the tallow. I have known some care-

less boys and girls (indeed, I have known it

happen to careful people as well) who, having

washed their hands and wiped them with a

towel, have thrown the towel over the side of

the basin, and before long it has drawn all the

water out of the basin and conveyed it to the

floor, because it happened to be thrown over

the side in such a way as to serve the purpose

of a siphon.(^) That you may the better see

the way in whicb the substances act one upon

another, I have here a vessel made of wire

gauze filled with water, and you may compare

it in its action to the cotton in one respect, or

to a piece of calico in the other. In fact, wicks

are sometimes made of a kind of wire gauze.

You will observe that this vessel is a porous

thing ; for if I pour a little water on to the top.

26 RISE OF FLUID THROUGH CANE.

it will run out at the bottom. You would be

puzzled for a good while if I asked you what

the state of this vessel is, what is inside it, and

why it is there ? The vessel is full of water,

and yet you see the water goes in and runs out

as if it were empty. In order to prove this to

you I have only to empty it. The reason is

this : the wire, being once wetted, remains wet;

the meshes are so small that the fluid is at-

tracted so strongly from the one side to the

other as to remain in the vessel, although it is

porous. In like manner, the particles of melted

tallow ascend the cotton and get to the top

;

other particles then follow by their mutual at-

traction for each other, and as they reach the

flame they are gradually burned.

Here is another application of the same prin-

ciple. You see this bit of cane. I have seen

boys about the streets, who are very anxious to

appear like men, take a piece of cane, and light

it, and smoke it, as an imitation of a cigar.

They are enabled to do so by the permeability

of the cane in one direction, and by its capil-

larity. If I place this piece of cane on a plate

containing some camphene (which is very much

WHY FLAME DOES NOT REACH THE CUP. 27

like paraffine in its general character), exactly

in the same manner as the blue fluid rose

through the salt will this fluid rise through the

piece of cane. There being no pores at the

side, the fluid can not go in that direction, but

must pass through its length. Already the

fluid is at the top of the cane ; now I can light

it and make it serve as a candle. The fluid

has risen by the capillary attraction of the

piece of cane, just as it does through the cotton

in the candle.

Now the only reason why the candle does

not burn all down the side of the wick is that

the melted tallow extinguishes the flame. You

know that a candle, if turned upside down, so

as to allow the fuel to run upon the wick, will

be put out. The reason is, that the flame has

not had time to make the fuel hot enough . to

burn, as it does above, where it is carried in

small quantities into the wick, and has all the

effect of the heat exercised upon it.

There is another condition which you must

learn as regards the candle, without which you

would not be able fully to understand the phi-

losophy of it, and that is the vaporous condition

28 COMBUSTIBLE VAPOR FROM A CANDLE.

of the fuel. In order that you may understand

that, let me show you a very pretty but verj^

commonplace experiment. If you blow a can-

dle out cleverly, you will see the vapor rise

from it. You have, I know, often smelt the

vapor of a blown-out candle, and a very bad

smell it is ; but if you blow it out cleverly,

you will be able to see pretty well the vapor

into which this solid matter is transformed. I

will blow out one of these candles in such a

way as not to disturb the air around it by the

continuing action of my breath ; and now, if I

hold a lighted taper two or three inches from

the wick, you will observe a train of fire going

Fig. 2.

BRILLIANCY OF FLAME. 29

through the air till it reaches the candle. I

ara obliged to be quick and ready, because if I

allow the vapor time to cool, it becomes con-

densed into a liquid or solid, or the stream of

combustible matter gets disturbed.

!N^ow as to the shape or form of the flame.

It concerns us much to know about the condi-

tion which the matter of the candle finally as-

sumes at the top of the wick, where you have

such beauty and brightness as nothing but

combustion or flame can produce. You have

the glittering beauty of gold and silver, and

the still higher lustre of jewels like the ruby

and diamond ; but none of these rival the bril-

liancy and beauty of flame. What diamond

can shine like flame? It owes its lustre at

night-time to the very flame shining upon it.

The flame shines in darkness, but the light

which the diamond has is as nothing until the

flame shines upon it, when it is brilliant again.

The candle alone shines by itself and for itself,

or for those who have arranged the materials.

Now let us look a little at the form of the

flame as you see it under the glass shade. It

is steady and equal, and its general form is that

80 SHAPE OF FLAME.

which is represented in the diagram, varying

with atmospheric disturbances, and also vary-

Fig. 3.

ing according to the size of the candle. It is a

bright oblong, brighter at the top than toward

the bottom, with the wick in the middle, and,

besides the wick in the middle, certain darker

parts toward the bottom, where the ignition is

not so perfect as in the part above. I have a

drawing here, sketched many years ago by

Hooker, when he made his investigations. It

is the drawing of the flame of a lamp, but it

will apply to the flame of a candle. The cup

of the candle is the vessel or lamp ; the melted

spermaceti is the oil ; and the wick is common

ASCENDING CUKRENT OF HOT AIR. 81

to both. Upon that he sets this little flame,

and then he represents what is true, a certain

quantity of matter rising about it which you do

not see, and which, if you have not been here

before, or are not familiar with the subject, you

will not know of. He has here represented the

parts of the surrounding atmosphere that are

very essential to the flame, and that are always

present with it. There is a current formed,

which draws the flame out ; for the flame which

you see is really drawn out by the current, and

drawn upward to a great height, just as Hooker

has here shown you by that prolongation of the

current in the diagram. You may see this by

taking a lighted candle, and putting it in the

sun so as to get its shadow thrown on a piece

of paper. How remarkable it is that that

thing which is light enough to produce shadows

of other objects can be made to throw its ownshadow on a piece of white paper or card, so

that you can actually see streaming round the

flame something which is not part of the flame,

but is ascending and drawing the flame upward.

Now I am going to imitate the sunlight by ap-

plying the voltaic battery to the electric lamp.

82 SHADOW OF FLAME.

You now see our sun and its great luminosity

;

and by placing a candle between it and the

screen, we get the shadow of the flame. You

Fig. 4.

iiiliiiii

observe the shadow of the candle and of the

wick; then there is a darkish part, as repre-

sented in the diagram, and then a part which

is more distinct. Curiously enough, however,

what we see in the shadow as the darkest part

of the flame is, in reality, the brightest part

;

and here you see streaming upward the ascend-

ing current of hot air, as shown by Hooker,

which draws out the flame, supplies it with air,

and cools the sides of the cup of melted fuel.

ASCENT OF FLAME. 33

I can give you here a little farther illustra-

tion, for the purpose of showing you how flame

goes up or down according to the current. I

have here a flame—it is not a candle flame

—

but you can, no doubt, by this time generalize

enough to be able to compare one thing with

another : what I am about to do is to change the

ascending current that takes the flame upward

into a descending current. This I can easily

do by the little apparatus you see before me.

Fig. 5.

The flame, as I have said, is not a candle flame,

but it is produced by alcohol, so that it shall

not smoke too much. I will also color the

flame with another substance, (^) so that you may

G

84 CHANGE OF DIRECTION OF FLAME.

trace its course ; for, with, the spirit alone, you

could hardly see well enough to have the oppor-

tunity of tracing its direction. By lighting

this spirit of wine we have then a flame pro-

duced, and you observe that when held in the

air it naturally goes upward. You understand

now, easily enough, why flames go up under

ordinary circumstances: it is because of the

draught of air by w^hich the combustion is

formed. But now, by blowing the flame down,

you see I am enabled to make it go downward

into this little chimney, the direction of the

current being changed. Before we have con-

cluded this course of lectures we shall show you

a lamp in which the flame goes up and the

smoke goes down, or the flame goes down and

the smoke goes up. You see, then, that we

have the power in this way of varying the

flame in different directions.

There are now some other points that I must

bring before you. Many of the flames you see

here vary very much in their shape by the

currents of air blowing around them in different

directions ; but we can, if we like, make flames

so that they will look like fixtures, and we can

FLAMES OF DIFFERENT SIIArES. 35

photograph them—indeed, we have to photo-

graph them—so that they become fixed to us,

if we wish to find out every thing concerning

them. That, however, is not the only thing I

wish to mention. If I take a flame sufficiently

large, it does, not keep that homogeneous, that

uniform condition of shape, but it breaks out

with a power of life which is quite wonderful.

I am about to use another kind of fuel, but one

which is truly and fairly a representative of the

wax or tallow of a candle. I have here a laro-eoball of cotton, which will serve as a wick.

And, now that I have immersed it in spirit and

applied a light to it, in what way does it differ

from an ordinary candle ? Why, it differs very

much in one respect, that we have a vivacity

and power about it, a beauty and a life entirely

different from the light presented by a candle.

You see those fine tongues of flame rising up.

You have the same general disposition of the

mass of the flame from below upward, but, in

addition to that, you have this remarkable

breaking out into tongues which you do not

perceive in the case of a candle. Now, why is

this ? I must explain it to you, because, when

SQ GAME OF SN-APDRAGON.

you understand that perfectly, you will be able

to follow me better in what I have to say here-

after. I suppose some here will have made for

themselves the experiment I am going to show

you. Am I right in supposing that any body

here has played at snapdragon? I do not

know a more beautiful illustration of the phi-

losophy of flame, as to a certain part of its

history, than the game of snapdragon. First,

here is the dish ; and let me say, that when

you play snapdragon properly you ought to

have the dish well warmed;you ought also to

have warm plums, and warm brandy, which,

however, I have not got. When you have put

the spirit into the dish, you have the cup and

the fuel; and are not the raisins acting like

the wicks? I now throw the plums into the

dish, and light the spirit, and you see those

beautiful tongues of flame that I refer to.

You have the air creeping in over the edge of

the dish forming these tongues. Why? Be-

cause, through the force of the current and the

irregularity of the action of the flame, it can

not flow in one uniform stream. The air flows

in so irregularly that you have what would

ANALYSIS OF FLAME. 87

otherwise be a single image broken up into

a variety of forms, and each of these little

tongues has an independent existenc3 of its own.

Indeed, I might say, you have here a multitude

of independent candles. You must not imagine,

because you see these tongues all at once, that

the flame is of this particular shape. A flame

of that shape is never so at any one time.

Kever is a body of flame, like that which you

just saw rising from the ball, of the shape it

appears to you. It consists of a multitude of

different shapes, succeeding each other so fast

that the eye is only able to take cognizance of

them all at once. In former times I purposely

analyzed a flame of that general character, and

the diagram shows you the different parts of

Fig. G.

88 ANALYSIS OF FLAME.

whicli it is composed. They do not occur all

at once ; it is only because we see these shapes

in such rapid succession that they seem to us

to exist all at one time.

It is too bad that we have not got farther

than my game of snapdragon ; but we must not,

under any circumstances, keep you be3^ond your

time. It will be a lesson to me in future to

hold you more strictly to the philosophy of the

thing than to take up your time so much with

these illustrations.

WHEKE DOES A CANDLE GO TO? 39

LECTUEE II.

A candle: brightness of the flame.—AIR necessary for COMBUSTION.— PRO-

DUCTION OF WATER.

We were occupied the last time we met in

considering tlie general character and arrange-

ment as regards the fluid portion of a candle,

and the way in which that fluid got into the

place of combustion. You see, when we have

a candle burning fairly in a regular, steady at-

mosphere, it will have a shape something like

the one shown in the diagram, and will look

pretty uniform, although very curious in its

character. And now I have to ask j^our at-

tention to the means by which we are enabled

to ascertain what happens in any particular

part of the flame ; why it happens ; what it

does in happening; and where, after all, the

whole candle goes to ; because, as you know

very well, a candle being brought before us

and burned, disappears, if burned properly,

40 PRODUCTS OF COMBUSTION.

without the least trace of dirt in the candle-

stick ; and this is a very curious circumstance.

In order, then, to examine this candle carefully,

I have arranged certain apparatus, the use of

which you will see as I go on. Here is a can-

dle ; I am about to put the end of this glass

tube into the middle of the flame—into that

part which old Hooker has represented in the

diagram as being rather dark, and which you

can see at any time if you will look at a candle

carefully, without blowing it about. We will

examine this dark part first.

Fig. 1.

VAPOR FROM INTERIOR OF FLAME. 41

Now I take this bent glass tube, and intro-

duce one end into that part of the flame, and

you see at once that something is coming from

the flame, out at the other end of the tube;

and if I put a flask there, and leave it for a

little while, you will see that something from

the middle part of the flame is gradually drawn

out, and goes through the tube, and into that

flask, and there behaves very differently from

what it does in the open air. It not only es-

capes from the end of the tube, but falls down

to the bottom of the flask like a heav}^ sub-

stance, as indeed it is. We find that this is

the wax of the candle made into a vaporous

fluid—not a gas. (You must learn the differ-

ence between a gas and a vapor : a gas remains

permanent; a vapor is something that will

condense.) If you blow out a candle, you per-

ceive a very nasty smel], resulting from the

condensation of this vapor. That is very dif-

ferent from what you have outside the flame

;

and, in order to make that more clear to you,

I am about to produce and set fire to a larger

portion of this vapor; for what we have in

the small way in a candle, to understand

42 COMBUSTIBLE VAPOR FROM WAX.

thoroughly, we must, as philosophers, produce

in a larger way, if needful, that we may ex-

amine the different parts. And now Mr. An-

derson will give me a source of heat, and I am

about to show you what that vapor is. Here

is some wax in a glass flask, and I am going

to make it hot, as the inside of that candle-

flame is hot, and the matter about the wick is

hot. [The lecturer placed some wax in a glass

flask, and heated it over a lamp.] Now I

dare say that is hot enough for me. You see

that the wax I put in it has become fluid, and

there is a little smoke coming from it. Weshall very soon have the vapor rising up. I

will make it still hotter, and now we get more

of it, so that I can actually pour the vapor

out of the flask into that basin, and set it on

fire there. This, then, is exactly the same kind

of vapor as we have in the middle of the can-

dle ; and that you may be sure this is the case,

let us try whether we have not got here, in

this flask, a real combustible vapor out of the

middle of the candle. [Taking the flask into

which the tube from the candle proceeded, and

introducing a lighted taper.] See how it

COMBUSTION OF THE VAPOIl. 43

burns. ISTow this is the vapor from the middle

of the candle, produced by its own heat ; and

that is one of the first things you have to con-

sider with respect to the progress of the wax in

the course of its combustion, and as regards the

changes it undergoes. I will arrange another

tube carefully in the flame, and I should not

wonder if we were able, by a little care, to get

that vapor to pass through the tube to the

other extremity, where we will light it, and

obtain absolutely the flame of the candle at a

place distant from it. Now, look at that. Is

Fig. S.

not that a very pretty experiment? Talk

about laying on gas—why, we can actually lay

on a candle ! And you see from this that there

44 DISTRIBUTION OF HEAT IN A FLAME.

are clearly two different kinds of action—one

tlie 2)''^oduction of tlie vapor, and the other the

combustion of it— both of which take place in

particular parts of the candle.

I shall get no vapor from that part which is

already burnt. If I raise the tube (Fig. 7) to

the upper part of the flame, so soon as the

vapor has been swept out what comes away

will be no longer combustible; it is already

burned. IIow burned? Why, burned thus:

In the middle of the flame, where the wick is,

there is this combustible vapor; on the out-

side of the flame is the air w^hich we shall find

necessary for the burning of the candle ; be-

tween the two, intense chemical action takes

place, whereby the air and the fuel act upon

each other, and at the very same time that we

obtain light the vapor inside is destroyed. If

you examine where the heat of a candle is, } ou

will find it very curiously arranged. Suppose

I take this candle, and hold a piece of paper

close upon the flame, where is the heat of that

flame? Do you not see that it is 7ioi in the

inside? It is in a ring, exactly in the place

where I told you the chemical action was ; and

AIR NECESSARY FOR COMBUSTION. 45

even in mj irregular mode of making the ex-

periment, if there is not too mucli disturbance,

there will always be a ring. This is a good

experiment for 3^ou to make at home. Take a

strip of paper, have the air in the room quiet,

and put the piece of paper right across the

middle of the flame—(I must not talk while I

make the experiment)—and you will find that

it is burnt in two places, and that it is not

burnt, or very little so, in the middle; and

when you have tried the experiment once or

twice, so as to make it nicely, you will be very

interested to see where the heat is, and to find

that it is where the air and the fuel come to-

gether.

This is most important for us as we proceed

with our subject. Air is absolutely necessary

for combustion ; and, w^hat is more, I must have

you understand that fresh air is necessary, or

else we should be imperfect in our reasoning

and our experiments. Here is a jar of air ; I

place it over a candle, and it bums very nicely

in it at first, showing that what I have said

about it is true ; but there will soon be a change.

See how the flame is drawing upward, present-

46 THE ARGAND LAMP.

Ij fading, and at last going out. And going

out, wliy ? Not because it wants air merel}^,

for the jar is as full now as it was before ; but

it wants pure, fresh air. The jar is fall of air,

partly changed, partly not changed ; but it

does not contain suf&cient of the fresh air

which is necessary for the combustion of a

candle. These are all points which we, as

young chemists, have to gather up ; and if we

look a little more closely into this kind of

action, we shall find certain steps of reasoning

extremely interesting. For instance, here is

the oil-lamp I showed you—an excellent lamp

for our experiments— the old Argand lamp.

I now make it like a candle [obstructing the

passage of air into the centre of the flame]

;

there is the cotton ; there is the oil rising up in

it; and there is the conical flame. It burns

poorly because there is a partial restraint of air.

I have allowed no air to get to it save round

the outside of the flame, and it does not burn

well. I can not admit more air from the out-

side, because the wick is large ; but if, as Ar-

gand did so cleverly, I open a passage to the

middle of the flame, and so let air come in

SOOT FROM IMPERFECT COMBUSTION. 47

there, you will see how much more beautifully

it burns. If I shut the air off, look how it

smokes ; and why ? We have now some very

interesting points to study : we have the case

of the combustion of a candle ; we have the

case of a candle being put out by the want of

air; and we have now the case of imperfect

combustion, and this is to us so interesting that

I want you to understand it as thoroughly as

you do the case of a candle burning in its best

possible manner. I will now make a great

flame, because w^e need the largest possible

illustrations. Here is a larger wick [burning

turpentine on a, ball of cotton]. All these

things are the same as candles, after all. If

we have larger wicks, we must have a larger

supply of air, or we shall have less perfect com-

bustion. Look, now, at this black substance

going up into the atmosphere ; there is a regu-

lar stream of it. I have provided means to

carry off the imperfectly-burned part, lest it

should annoy you. Look at the soots that fly

off from the flame ; see what an imperfect com-

bustion it is, because it can not get enough air.

What, then, is happening? Why, certain

48 DIFFERENT CONDITIONS OF FLAME.

things which arc necessary to the combustion

of a candle are absent, and very bad results are

accordingly produced ; but we see what happens

to a candle when it is burnt in a pure and prop-

er state of air. At the time when I showed

you this charring by the ring of flame on the

one side of the paper, I might have also shown

you, by turning to the other side, that the

burning of a candle produces the same kind of

soot—charcoal, or carbon.

But, before I show that, let me explain to

you, as it is quite necessary for our purpose,

that, though I take a candle, and give you, as

the general result, its combustion in the form

of a flame, we must see whether combustion is

always in this condition, or whether there are

other conditions of flame ; and we shall soon

discover that there are, and that they are most

important to us. I think, perhaps, the best

illustration of such a point to us, as juveniles, is

to show the result of strong contrast. Here is

a little gunpowder. You know that gunpowder

burns with flame ; we may fairly call it flame.

It contains carbon and other materials, which

altogetber cause it to burn with a flame. And

COMBUSTION WITH AND WITHOUT FLAME. 49

here is some pulverized iron, or iron filings.

Now I jDurpose burning these two things to-

gether. I have a little mortar in which I will

mix them. (Before I go into these experi-

ments, let me hope that none of you, by trying

to repeat them, for fun's sake, will do any harm.

These things may all be very properly used if

you take care, but without that much mischief

will be done.) Well, then, here is a little gun-

powder, which I put at the bottom of that little

wooden vessel, and mix the iron filings up with

it, my object being to make the gunpowder set

fire to the filings and burn them in the air, and

thereby show the difference between substances

burning with flame and not with flame. Here

is the mixture ; and when I set fire to it you

must watch the combustion, and you will see

that it is of two kinds. You will see the gun-

powder burning with a flame and the filings

thrown up. You will see them burning too,

but without the production of flame. They

will each burn separately. [The lecturer then

ignited the mixture.] There is the gunpowder,

which burns with a flame, and there are the

filings : they burn with a different kind of com-

D

50 COMBUSTION OF LYCOPODIUM.

bustion. You see, tlien, these two great dis-

tinctions; and upon these differences depend

all the utility and all the beauty of flame which

we use for the purpose of giving out light.

When we use oil, or gas, or candle for the pur-

pose of illumination, their fitness all depends

upon these different kinds of combustion.

There are such curious conditions of flame

that it requires some cleverness and nicety of

discrimination to distinguish the kinds of com-

bustion one from another. For instance, here

is a jpowder which is very combustible, consist-

ing, as you see, of separate little particles. It is

called hjcoijodium^i^') and each of these particles

can produce a vapor, and produce its own

flame; but, to see them burning, you would

imagine it was all one flame. I will now set

fire to a quantity, and you will see the effect.

We saw a cloud of flame, apparently in one

body ; but that rushing noise [referring to the

sound produced by the burning] was a proof

that the combustion was not a continuous or

regular one. This is the lightning of the pan-

tomimes, and a very good imitation. [The ex-

periment was twice repeated by blowing lyco-

SOOT FROM A LUMINOUS FLAME. 51

podium from a glass tube tlirougli a spirit

flame.] This is not an example of combustion

like that of the filings I have been speaking of,

to which we must now return.

Suppose I take a candle and examine that

part of it which appears brightest to our eyes.

Why, there I get these black particles, which

already you have seen many times evolved from

the flame, and which I am now about to evolve

in a different way. I will take this candle and

clear away the gutterage, which occurs by rea-

son of the currents of air ; and if I now arrange

a glass tube so as just to dip into this luminous

part, as in our first experiment, only higher,

you see the result. In place of having the

same white vapor that you had before, you

will now have a black vapor. There it goes,

as black as ink. It is certainly very different

from the white vapor ; and when we put a light

to it we shall find that it does not burn, but

that it puts the light out. Well, these parti-

cles, as I said before, are just the smoke of the

candle; and this brings to mind that old em-

ployment which Dean Swift recommended to

servants for their amusement, namely, writing

52 CAUSE OF THE LUMINOSITY OF FLAME.

on the ceiling of a room with a candle. But

what is that black substance ? Why, it is the

same carbon which exists in the candle. Howcomes it out of the candle ? It evidently ex-

isted in the candle, or else we should not have

had it here. And now I want you to follow

me in this explanation. You would hardly

think that all those substances which fly about

London, in the form of soots and blacks, are

the very beauty and life of the flame, and which

are burned in it as those iron filings were burn-

ed here. Here is a piece of wire gauze, which

will not let the flame go through it, and I think

you will see, almost immediately, that when I

bring it low enough to touch that part of the

flame which is otherwise so bright, it quells

and quenches it at once, and allows a volume

of smoke to rise up.

I want you now to follow me in this point

—

that whenever a substance burns, as the iron

filings burnt in the flame of gunpowder, with-

out assuming the vaporous state (whether it

becomes liquid or remains solid), it becomes

exceedingly luminous. I have here taken three

or four examples apar* from the candle on

CAUSE OF THE LUMINOSITY OF FLAME. 53

purpose to illustrate this point to you, because

what I have to say is applicable to all sub-

stances, whether they burn or whether they do

not burn—that they are exceedingly bright if

they retain their solid state, and that it is to

this presence of solid particles in the candle-

flame that it owes its brilliancy.

Here is a platinum wire, a body which, does

not change by heat. If I heat it in this flame,

see how exceedingly luminous it becomes. I

will make the flame dim for the purpose of

giving a little light only, and yet you will see

that the heat which it can give to that plati-

num wire, though far less than the heat it has

itself, is able to raise the platinum wire to a

far higher state of effulgence. This flame has

carbon in it ; but I will take one that has no

carbon in it. There is a material, a kind of

fuel—a vapor or gas, whichever you like to

call it—in that vessel, and it has no solid par-

ticles in it ; so I take that because it is an ex-

ample of flame itself burning without any solid

matter whatever ; and if I now put this solid

substance in it, you see what an intense heat it

has, and how brightly it causes the solid body

64 THE LIME LIGHT.

to glow. This is the pipe through v/hich we

convey this particular gas, which we call hy-

drogen, and which you shall know all about

next time we meet. And here is a substance

called oxygen, by means of which this hydro-

gen can burn ; and although we produce, by

their mixture, far greater heat(^) than you can

obtain from the candle, yet there is very little

light. If, however, I take a solid substance,

and put that into it, we produce an intense

light. If I take a piece of lime, a substance

which will not burn, and which will not vap-

orize by the heat (and because it does not vap-

orize remains solid, and remains heated), you

will soon observe what happens as to its glow-

ing. I have here a most intense heat produced

by the burning of hydrogen in contact with

the oxygen; but there is as yet very little

light—not for want of heat, but for want of

particles which can retain their solid state ; but

when I hold this piece of lime in the flame of

the hydrogen as it burns in the oxygen, see

how it glows ! This is the glorious lime light,

which rivals the voltaic light, and which is al-

most equal to sunlight. I have here a piece

COMBUSTION OF PHOSPHORUS. 65

of carbon or charcoal, which will burn and give

us light exactly in the same manner as if it

were burnt as part of a candle. The heat that

is in the flame of a candle decomposes the va-

por of the wax, and sets free the carbon par-

ticles ; they rise up heated and glowing as this

now glows, and then enter into the air. But

the particles, when burnt, never pass off from

a candle in the form of carbon. They go off

into the air as a perfectly invisible substance,

about which we shall know hereafter.

Is it not beautiful to think that such a proc-

ess is going on, and that such a dirty thing as

charcoal can become so incandescent? You

see it comes to this—that all bright flames con-

tain these solid particles ; all things that burn

and produce solid particles, either during the

time they are burning, as in the candle, or im-

mediately after being burnt, as in the case of

the gunpowder and iron filings— all these

things give us this glorious and beautiful

light.

I will give you a few illustrations. Here is

a piece of phosphorus, which burns with a

bright flame. Yery well ; we may now con-

56 COMBUSTION OF PHOSPHORUS.

elude that phosphorus will produce, either at

the moment that it is burning or afterward,

these solid particles. Here is the phosphorus

Fig. 9.

lighted, and I cover it over with this glass for

the purpose of keeping in what is produced.

What is all that smoke ? That smoke consists

of those very particles which are produced by

the combustion of the phosphorus. Here again

are two substances. This is chlorate of potassa,

and this other sulphuret of antimony. I shall

mix these together a little, and then they may

be burnt in many ways. I shall touch them

with a drop of sulphuric acid, for the purpose

of giving you an illustration of chemical action,

and they will instantly burn.(^) [The lecturer

then ignited the mixture by means of sulphuric

COMBUSTION OF ZINC. 57

acid.] Now, from the appearance of things,

you can judge for yourselves whether they

produce solid matter in burning. I have given

you the train of reasoning which will enable

you to say whether they do or do not ; for what

is this bright flame but the solid particles pass-

ing off?

Mr. Anderson has in the furnace a very hot

crucible. I am about to throw into it some

zinc filings, and they will burn with a flame

like gunpowder. I make this experiment be-

cause you can make it well at home. Now I

want you to see what will be the result of the

combustion of this zinc. Here it is burning

—

burning beautifully like a candle, I may say.

But what is all that smoke, and what are those

little clouds of wool which will come to you if

you can not come to them, and make them-

selves sensible to you in the form of the old

philosophic wool, as it was called ? "We shall

have left in that crucible, also, a quantity of

this woolly matter. But I will take a piece of

this same zinc, and make an experiment a little

more closely at home, as it were. You will

have here the same thing happening. Here is

58 COMBUSTION OF ZINC.

the piece of zinc; there [pointing to a jet of

hydrogen] is the furnace, and we will set to

work and try and burn the metal. It glows,

you see ; there is the combustion ; and there is

the white substance into which it burns. And

so, if I take that flame of hydrogen as the rep-

resentative of a candle, and show you a sub-

stance like zinc burning in the flame, you will

see that it was merely during the action of

combustion that this substance glowed—while

it was kept hot; and if I take a flame of hy-

drogen and put this white substance from the

zinc into it, look how beautifully it glows, and

just because it is a solid substance.

I will now take such a flame as I had a mo-

ment since, and set free from it the particles

of carbon. Here is some camphene, which will

burn with a smoke ; but if I send these parti-

cles of smoke through this pipe into the hydro-

gen flame you will see they will burn and be-

come luminous, because we heat them a second

time. There they are. Those are the parti-

cles of carbon reignited a second time. They

are those particles which you can easily see by

holding a piece of paper behind them, and

LUMINOSITY OF COAL-GAS FLA:,:e. 59

which, while they are in the flame, are ignited

by the heat produced, and, when so ignited,

produce this brightness. "When the particles

are not separated you get no brightness. The

flame of coal-gas owes its brightness to the

separation, during combustion, of these parti-

cles of carbon, which are equally in that as in a

candle. I can very quickly alter that arrange-

ment. Here, for instance, is a bright flame of

gas. Supposing I add so much air to the flame

as to cause it all to burn before those particles

are set free, I shall not have this brightness;

and I can do that in this way : If I place over

the jet this wire-gauze cap, as you see, and then

light the gas over it, it burns with a non-lu-

minous flame, owing to its having plenty of

air mixed with it before it burns ; and if I raise

the gauze, you see it does not burn below.(^°)

There is plenty of carbon in the gas ; but, be-

cause the atmosphere can get to it, and mix

with it before it burns, you see how pale and

blue the flame is. And if I blow upon a bright

gas-flame, so as to consume all this carbon

before it gets heated to the glowing point, it

will also burn blue. [The lecturer illustrated

60 DIFFERENT RESULTS OF COMBUSTION.

bis remarks by blowing on the gas-light.] The

only reason why I have not the same bright

light when I thus blow upon the flame is that

the carbon meets with sufficient air to burn it

before it gets separated in the flame in a free

state. The difiference is solely due to the solid

particles not being separated before the gas is

burnt.

You observe that there are certain products

as the result of the combustion of a candle, and

that of these products one portion may be con-

sidered as charcoal, orvsoot ; that charcoal, when

afterward burnt, produces some other product

;

and it concerns us very much now to ascertain

what that other product is. We showed that

something was going away ; and I want you

now to understand how much is going up into

the air ; and for that purpose we will have com-

bustion on a little larger scale. From that

candle ascends heated air, and two or three

experiments will show you the ascending cur-

rent ; but, in order to give you a notion of the

quantity of matter which ascends in this way,

I will make an experiment by which I shall

try to imprison some of the products of this

THE FIRE-BALLOON. 61

combustion. For this purpose I have here what

boys call a fire-balloon ; I use this fire-balloon

Fij. 10.

merely as a sort of measure of the result of

the combustion we are considering ; and I am

about to make a flame in such an easy and

simple manner as shall best serve my present

purpose. This plate shall be the "cup," we

will so say, of the candle ; this spirit shall be

our fuel ; and I am about to place this chimney

62 THE FIRE-BALLOON.

over it, because it is better for me to do so than

to let things proceed at random. Mr. Anderson

will now light the fuel, and here at the top we

shall get the results of the combustion. What

we get at the top of that tube is exactly the

same, generally speaking, as you get from the

combustion of a candle ; but we do not get a

luminous flame here, because we use a substance

which is feeble in carbon. I am about to put

this balloon—not into action, because that is not

my object—but to show you the effect which

results from the action of those products which

arise from the candle, as they arise here from

the furnace. [The balloon was held over the

chimney, when it immediately commenced to

fill.] You see how it is disposed to ascend

;

but we must not let it up, because it might

come in contact with those upper gas-lights,

and that would be very inconvenient. [The

upper gas-lights were turned out at the request

of the lecturer, and the balloon was allowed to

ascend.] Does not that show you what a large

bulk of matter is being evolved ? Now there

is going through this tube [placing a large

glass tube over a candle] all the products of

WATER A PRODUCT OF COMBUSTION. 63

that candle, and you will presently see that the

tube will become quite opaque. Suppose I take

another candle, and place it under a jar, and

then put a light on the other side, just to show

you what is going on. You see that the sides

of the jar become cloudy, and the light begins

to burn feebly. It is the products, you see,

which make the light so dim, and this is the

same thing which makes the sides of the jar so

opaque. If you go home, and take a spoon that

has been in the cold air, and hold it over a

candle—not so as to soot it—you will find that

it becomes dim just as that jar is dim. If you

can get a silver dish, or something of that kind,

you will make the experiment still better ; and

now, just to carry your thoughts forward to the

time we shall next meet, let me tell you that it

is water which causes the dimness, and when we

next meet I will show you that we can make

it, without difficulty, assume the form of a

liquid.

64: PRODUCTS FROM THE CANDLE.

LECTURE III.

products: water from the combustion.—NATURE of water.— A COMPOUND.— HY-

DROGEN.

I DARE say you well remember that when we

parted we had just mentioned the word " prod-

ucts" from the candle ; for when a candle burns

we found we were able, by nice adjustment,

to get various products from it. There was

one substance which was not obtained when

the candle was burning properly, which was

charcoal or smoke> and there was some other

substance that went upward from the flame

which did not appear as smoke, but took some

other form, and made part of that general cur-

rent which, ascending from the candle uj)-

ward, becomes invisible, and escapes. There

were also other products to mention. You

remember that in that rising current having

its origin at the candle we found that one part

was condensable against a cold spoon, or against

niODUCTS FROM THE CANDLE. 65

a clean plate, or any other cold thing, and an-

other part was incondensable.

We will first take the condensable part, and

examine it, and, strange to say, we find that

that part of the product is just water—nothing

but water. On the last occasion I spoke of it

incidentally, merely saying that water was pro-

duced among the condensable products of the

candle ; but to-day I wish to draw your atten-

tion to water, that we may examine it care-

fully, especially in relation to this subject, and

also with respect to its general existence on the

surface of the globe.

Now, having previously arranged an experi-

ment for the purpose of condensing water from

the products of the candle, my next point will

be to show you this water ; and perhaps one of

the best means that I can adopt for showing its

presence to so many at once is to exhibit a very

visible action of water, and then to apply that

test to what is collected as a drop at the bottom

of that vessel. I have here a chemical sub-

stance, discovered by Sir Humphrey Davy,

which has a very energetic action upon water,

which I shall use as a test of the presence of

E

66 TEST FOR THE TEESEXCE OF WATER.

water. If I take a little piece of it—it is called

potassium, as coming from potasli—if I take a

little piece of it, and throw it into that basin,

you see how it shows the presence of water by

lighting up and floating about, burning with a

violet flame. I am now going to take away the

candle which has been burning beneath the

vessel containing ice and salt, and you see a

Fig. 11.

drop of water— a condensed product of the

candle—hanging from the under surface of the

dish. I will show you that potassium has the

same action upon it as upon the water in that

basin in the experiment we have just tried.

"WATER FROM A CANDLE. 67

See! it takes fire, and burns in just the same

manner. I will take another drop upon this

glass slab, and when I put the potassium on to

it, you see at once, from its taking lire, that

there is water present. Now that water was

produced by the candle. In the same manner,

if I put this spirit-lamp under that jar, you will

soon see the latter become damp, from the dew

which is deposited upon it—that dew being the

result of combustion ; and I have no doubt you

will shortly see, by the drops of water which

fall upon the paper below, that there is a good

deal of water produced from the combustion of

the lamp. I will let it remain, and you can

afterward see how much water has been col-

lected. So, if I take a gas-lamp, and put any

cooling arrangement over it, I shall get water

—water being likewise produced from the com-

bustion of gas. Here, in this bottle, is a quan-

tity of water— perfectly pure, distilled water,

produced from the combustion of a gas-lamp

—

in no point different from the water that you

distill from the river, or ocean, or spring, but

exactly the same thing. Water is one individ-

ual thing ; it never changes. We can add to it

b<5 WATER A IlESULT OF COMBUSTION.

by careful adjustment for a little while, or we

can take it apart and get other things from it

;

but water, as water, remains always the same,

either in a solid, liquid, or fluid state. Here

again [holding another bottle] is some water

produced by the combustion of an oil-lamp. Apint of oil, when burnt fairly and properlj^,

produces rather more than a pint of water.

Here, again, is some water, produced by a rath-

er long experiment, from a wax candle. Andso we can go on with almost all combustible

substances, and find that if they burn with a

flame, as a candle, they produce water. You

may make these experiments yourselves: the

head of a poker is a very good thing to try

with, and if it remains cold long enough over

the candle, you may get water condensed in

drops on it ; or a spoon, or ladle, or any thing

else may be used, provided it be clean, and can

carry off the heat, and so condense the water.

And now—to go into the history of this

wonderful production of water from combus-

tibles, and by combustion—I must first of all

tell you that this water may exist in different

conditions ; and although you may now be ac-

DIFFERENT CONDITIONS OF WATER. 69

quainted with all its forms, they still require

us to give a little attention to them for the

present ; so that we may perceive how the wa-

ter, while it goes through its Protean changes,

is entirely and absolutely the fame thing,

whether it is produced from a candle, by com-

bustion, or from the rivers or ocean.

First of all, water, when at the coldest, is ice.

Kow we philosophers—I hope that I may class

you and myself together in this case—speak of

water as water, whether it be in its solid, or

liquid, or gaseous state—we speak of it chemi-

cally as water. Water is a thing compounded

of two substances, one of which we have derived

from the candle, and the other we shall find

elsewhere. Water may occur as ice ; and you

have had most excellent opportunities lately of

seeing this. Ice changes back into water—for

we had on our last Sabbath a strong instance

of this change by the sad catastrophe which

occurred in our own house, as well as in the

houses of many of our friends— ice changes

back into water when the temperature is raised;

water also changes into steam when it is warmed

enough. The water which we have here before

70 WATER CHANGED INTO ICE.

US is in its densest state ;(^^) and, although it

changes in weight, in condition, in form, and

in many other qualities, it still is water; and

whether we alter it into ice by cooling, or

whether we change it into steam by heat, it

increases in volume— in the one case very

strangely and powerfully, and in the other case

very largely and wonderfully. For instance, I

will now take this tin cjdinder, and pour a little

water into it, and, seeing how much water I

pour in, you may easily estimate for yourselves

how high it will rise in the vessel : it will cov-

er the bottom about two inches. I am now

about to convert the water into steam for the

purpose of showing to you the different vol-

umes which water occupies in its different

states of water and steam.

Let us now take the case of water changing

into ice : we can effect that by cooling it in a

mixture of salt and pounded ice(^^)—and I shall

do so to show you the expansion of water into a

thing of larger bulk when it is so changed.

These bottles [holding one] are made of strong

cast iron, very strong and very thick—I suppose

they are the third of an inch in thickness ; they

WATER CHANGED INTO STEAJI. 71

arc very carefully filled with water, so as to

exclude all air, and then they are screwed down

tight. We shall see that when we freeze the

water in these iron vessels, they will not be able

to hold the ice, and the expansion within them

will break them in pieces as these [pointing to

some fragments] are broken, which have been

bottles of exactly the same kind. I am about

to put these two bottles into that mixture of ice

and salt for the purpose of showing that when

water becomes ice it changes in volume in this

extraordinary way.

In the mean time, look at the change which

has taken place in the water to which we have

applied heat; it is losing its fluid state. You

may tell this by two or three circumstances.

I have covered the mouth of this glass flask,

in which water is boiling, with a watch-glass.

Do you see what happens? It rattles away

like a valve chattering, because the steam

rising from the boiling water sends the valve

up and down, and forces itself out, and so

makes it clatter. You can very easily perceive

that the flask is quite full of steam, or else it

would not force its way out. You see also that

72 EXPANSIVE FORCE OF FREEZING WATER.

the flask contains a substance very much larger

than the water, for it fills the whole of the flask

over and over again, and there it is blowing

away into the air ; and yet you can not observe

any great diminution in the bulk of the water,

which shows you that its change of bulk is very

great when it becomes steam.

I have put our iron bottles containing water

into this freezing mixture, that you may see

what happens. Ko communication will take

place, 3^ou observe, between the water in the

bottles and the ice in the outer vessel. But

there will be a conveyance of heat from the one

to the other, and if we are successful—we are

making our experiment in very great haste—

I

expect you will by-and-by, so soon as the cold

has taken possession of the bottles and their

contents, hear a pop on the occasion of the

bursting of the one bottle or the other, and,

when we come to examine the bottles, we shall

find their contents masses of ice, partly inclosed

by the covering of iron which is too small for

them, because the ice is larger in bulk than the

water. You know very well that ice floats

upon water; if a boy falls through a hole into

CONVERSION OF WATER INTO STEAM. 73

the water, he tries to get on tlie ice again to

float him up. Why does the ice float? Think

of that, and philosophize. Because the ice is

larger than the quantity of water which can

produce it, and therefore the ice weighs the

lighter and the water is the heavier.

To return now to the action of heat on water.

See what a stream of vapor is issuing from this

tin vessel. You observe, we must have made

it quite full of steam to have it sent out in that

great quantity. And now, as we can convert

the water into steam by heat, we convert it

back into liquid water by the application of

cold. And if we take a glass, or any other cold

thing, and hold it over this steam, see howsoon it gets damp with water : it will condense

it until the glass is warm— it condenses the

water which is now running down the sides of

it. I have here another experiment to show

the condensation of water from a vaporous state

back into a liquid state, in the same way as the

vapor, one of the products of the candle, was

condensed against the bottom of the dish and

obtained in the form of water; and to show

you how truly and thoroughly these changes

7-i CONTRACTION OF STEAM AVIIEN CONDENSED.

take place, I will take this tin flask, which is

now full of steam, and close the top. We shall

see what takes place when we cause this water

or steam to return back to the fluid state by

pouring some cold water on the outside. [The

lecturer poured the cold water over the vessel,

when it immediately collapsed.] You see what

Fig. 12.

has happened. K I had closed the stopper, and

still kept the heat applied to it, it would have

burst the vessel;yet, when the steam returns

to the state of water, the vessel collapses, there

RELATIVE BULKS OF STEAM AND WATER. 75

being a vacuum produced inside by the con-

densation of the steam. I show you these

experiments for the purpose of pointing out

that in all these occurrences there is nothing

that changes the water into any other thing ; it

still remains water ; and so the vessel is obliged

to give way, and is crushed inward, as in the

other case, by the farther application of heat, it

would have been blown outward.

And what do you think the bulk of that

water is when it assumes the vaporous condi-

tion ? You see that cube [pointing to a cubic

Fig. 13.

23B.

foot]. There, by its side, is a cubic inch, exact-

ly the same shape as the cubic foot, and that

bulk of water [the cubic inch] is sufficient to ex-

pand into that bulk [the cubic foot] of steam

;

and, on the contrary, the application of cold will

contract that large quantity of steam into this

76 EXPANSIVE FORCE OF FREEZING WATER.

small quantity of water. [One of the iron

bottles burst at that moment.] Ah ! There is

one of our bottles burst, and here, you see, is a

crack down one side an eighth of an inch in

width. [The other now exploded, sending the

freezing mixture in all directions.] This other

bottle is also broken ; although the iron was

nearly half an inch thick, the ice has burst it

asunder. These changes always take place in

water; they do not require to be always pro-

duced by artificial means ; we only use them

here because we want to produce a small winter

round that little bottle instead of a long and

severe one. But if you go to Canada, or to the

North, you will find the temperature there out

of doors will do the same thing as has been

done here by the freezing mixture.

To return to our quiet philosophy. "We shall

not in future be deceived, therefore, by any

changes that are produced in water. Water is

the same every where, whether produced from

the ocean or from the flame of the candle.

Where, then, is this water which we get from a

candle ? I must anticipate a little, and tell you.

It evidently comes, as to part of it, from the

ACTIOX OF POTASSIUM ON WATER. 77

candle, but is it witliin the candle beforehand ?

No, it is not in the candle; and it is not in

the air around about the candle which is neces-

sary for its combustion. It is neither in one

nor the other, but it comes from their conjoint

action, a part from the candle, a part from the

air ; and this we have now to trace, so that we

may understand thoroughly what is the chemi-

cal history of a candle when we have it burning

on our table. How shall we get at this? I

myself know plenty of wa3's, but I want you to

get at it from the association in your own minds

of what I have already told you.

I think you can see a little in this way. Wehad just now the case of a substance which

acted upon the water in the way that Sir

Humphrey Davy showed us,(^^) and which I am

now going to recall to your minds by making

again an experiment upon that dish. It is a

thing which w^e have to handle very carefully

;

for you see, if I allow a little splash of water

to come upon this mass, it sets fire to part of it

;

and if there were free access of air, it would

quickly set fire to the whole. Now this is a

metal— a beautiful and bright metal— which

78 COMBUSTION OF ZINC.

rapidly changes in the air, and, as you know,

rapidly changes in water. I will put a piece on

the water, and you see it burns beautifully,

making a floating lamp, using the water in the

place of air. Again, if we take a few iron

filings or turnings and put them in water, we

And that they likewise undergo an alteration.

They do not change so much as this potassium

does, but t'hey change somewhat in the same

way ; they become rusty, and show an action

upon the water, though in a different degree

of intensity to what this beautiful metal does

;

but they act upon the water in the same man-

ner generally as this potassium. I want you

to put these different facts together in your

minds. I have another metal here [zinc], and

when we examined it with regard to the solid

substance produced by its combustion, we had

an opportunity of seeing that it burned ; and I

suppose, if I take a little strip of this zinc and

put it over the candle, you will see something

half way, as it were, between the combustion

of potassium on the water and the action of

iron—you see there is a sort of combustion. It

has burned, leaving a white ash or residuum

;

COMBUSTION OF IRON. 79

and here also wc find tliat the metal has a cer-

tain amount of action upon water.

By degrees we have learned how to modify

the action of these different substances, and to

make them tell us what we want to know.

And now, first of all, I take iron. It is a com-

mon thing in all chemical reactions, where we

get any result of this kind, to find that it is in-

creased by the action of heat ; and if we want

to examine minutely and carefully the action

of bodies one upon another, we often have to

refer to the action of heat. You are aware, I

believe, that iron filings burn beautifully in the

air ; but I am about to show you an experiment

of this kind, because it will impress upon you

what I am going to say about iron in its action

on water. If I take a flame and make it hol-

low—you know why, because I want to get air

to it and into it, and therefore I make it hol-

low—and then take a few iron filings and drop

them into the flame, you see how well they

burn. That combustion results from the chem-

ical action which is going on when we ignite

those particles. And so we proceed to consider

these different effects, and ascertain what iron

80 ACTION OF IRON ON STEAM.

will do wlicu it meets with water. It will tell

us the story so beautifully, so gradually and

regularly, that I think it will please you very

much.

I have here a furnace with a pipe going

through it like an iron gun-barrel, and I have

stuffed that barrel full of bright iron turnings,

and placed it across the fire to be made red-hot.

We can either send air through the barrel to

come in contact with the iron, or we can send

steam from this little boiler at the end of the

barrel. Here is a stop-cock which shuts off the

steam from the barrel until we wish to admit it.

There is some water in these glass jars, which

PRODUCT OF DECOMPOSITION OF STEAM. 81

I have colored blue, so that you may see what

happens. Now you know very well that any

steam I might send through that barrel, if it

went through into the water, would be con-

densed ; for you have seen that steam can not

retain its gaseous form if it be cooled down

;

you saw it here [pointing to the tin flask]

crushing itself into a small bulk, and causing

the flask holding it to collapse ; so that if I

were to send steam through that barrel it

would be condensed, supposing the barrel

were cold; it is therefore heated to perform

the experiment I am now about to show you.

I am going to send the steam through the bar-

rel in small quantities, and you shall judge for

yourselves, when you see it issue from the oth-

er end, whether it still remains steam. Steam

is condensible into water, and when you lower

the temperature of steam you convert it back

into fluid water ; but I have lowered the tem-

perature of the gas which I have collected in

this jar by passing it through water after it

has traversed the iron barrel, and still it does

not change back into water. I will take an-

other test and apply to this gas. (I hold the

F

82 PRODUCT OF DECOMPOSITION OF STEAM.

jar in an inverted position, or my substance

would escape.) If I now apply a light to the

mouth of the jar, it ignites with a slight noise.

That tells you that it is not steam ; steam puts

out a fire : it does not burn ; but you saw that

what I had in that jar burnt. We may obtain

this substance equally from water produced

from the candle flame as from any other source.

When it is obtained by the action of the iron

upon the aqueous vapor, it leaves the iron in

a state very similar to that in which these

filings were after they were burnt. It makes

the iron heavier than it was before. So long-

as the iron remains in the tube and is heated,

and is cooled again without the access of air or

water, it does not change in its weight; but

after having had this current of steam passed

over it, it then comes out heavier than it was

before, having taken something out of the

steam, and having allowed something else to

pass forth, which we see here. And now, as

we have another jar full, I will show you some-

thing most interesting. It is a combustible

gas ; and I might at once take this jar and set

fire to the contents, and show you that it is

PKOPERTIES OF THE NEW GAS. 83

combustible ; but I intend to show you more,

if I can. It is also a very light substance.

Steam will condense ; this body will rise in the

air, and not condense. Suppose I take another

glass jar, empty of all but air : if I examine it

with a taper I shall find that it contains nothing

but air. I will now take this jar full of the

gas that I am speaking of, and deal with it as

though it were a light body ; I will hold both

upside down, and turn the one up under the

other; and that which did contain the gas

Fig. 15.

procured from the steam, what does it contain

now ? You will find it now only contains air.

But look ! Here is the combustible substance

[taking the other jar] which I have poured

out of the one jar into the other. It still pre-

serves its quality, and condition, and independ-

84 ACTION OF ZINC ON WATER.

ence, and therefore is the more worthy of our

consideration, as belonging to the products of a

candle.

Now this substance which we have just pre-

pared by the action of iron on the steam or

water, we can also get by means of those other

things which you have already seen act so well

upon the water. If I take a piece of potassium,

and make the necessary arrangements, it will

produce this gas ; and if instead a piece of zinc,

I find, when I come to examine it very care-

fully, that the main reason why this zinc can

not act upon the water continuously as the

other metal does is because the result of the

action of the water envelops the zinc in a kind

of protecting coat. We have learned in con-

sequence, that if we put into our vessel only

the zinc and water, they, by themselves, do not

give rise to much action, and we get no result.

But suppose I proceed to dissolve off this var-

nish— this encumbering substance— which I

can do by a little acid ; the moment I do this

I find the zinc acting upon the water exactly

as the iron did, but at the common temperature.

The acid in no way is altered except in its

HYDROGEN". 85

combination with the oxide of zinc which is

produced. I have now poured the acid into

the glass, and the effect is as though I were

applying heat to cause this boiling up. There

is something coming off from the zinc very

abundantly, which is not steam. There is a

jar full of it; and you will find that I have

exactly the same combustible substance remain-

ing in the vessel, when I hold it upside down,

that I produced during the experiment with

the iron barrel. This is what we get from

Fig. IG.

water, the same substance "^hich is contained

in the candle.

Let us now trace distinctly the connection

between these two points. This is hydrogen

—

a body classed among those things which in

86 HYDROGEN.

chemistry we call elements, because we can get

nothing else out of them. A candle is not an

elementary body, because we can get carbon

out of it ; we can get this hydrogen out of it, or

at least out of the water which it supplies.

And this gas has been so named hydrogen,

because it is that element which, in association

with another, generates water.* Mr. Anderson

having now been able to get two or three jars

of gas, we shall have a few experiments to

make, and I want to show you the best way of

making these experiments. I am not afraid to

show you, for I wish you to make experiments,

if you will only make them with care and at-

tention, and the assent of those around you.

As we advance in chemistry we are obliged to

deal with substances which are rather injurious

if in their wrong jDlaces ; the acids, and heat,

and combustible things we use might do harm

if carelessly employed. If you want to make

hydrogen, you can make it easily from bits of

zinc, and sulphuric or muriatic acid. Here is

what in former times was called the "philoso-

pher's candle." It is a little phial with a cork

* 'T^WjO, "water," and yevvau), "I generate."

THE PHlLOSOPHEll's CANDLE. 87

and a tube or pipe passing through it. And I

am now putting a few little pieces of zinc into

Fiq. 11

it. This little instrument I am going to apply

to a useful purpose in our demonstrations, for I

want to show you that you can prepare hy-

drogen, and make some experiments with it as

you please, at your own homes. Let me here

tell you why I am so careful to fill this phial

nearly, and yet not quite full. I do it because

the evolved gas, which, as you have seen, is

very combustible, is explosive to a considerable

extent when mixed with air, and might lead to

harm if you were to apply a light to the end of

that pipe before all the air had been swept out

88 PREPARATION OF HYDROGEN-.

of the space above the water. I am now about

to pour in the sulphuric acid. I have used

very little zinc and more sulphuric acid and

water, because I want to keep it at work for

some time. I therefore take care in this way

to modify the proportions of the ingredients so

that I may have a regular supply— not too

quick and not too slow. Supposing I now. take

a glass and put it upside down over the end of

the tube, because the hydrogen is light I expect

that it will remain in that vessel a little while.

We will now test the contents of our glass to

see if there be hydrogen in it; I think I am

safe in saying we have caught some [applying

a light]. There it is, you see. I will now

apply a light to the top of the tube. There is

the hydrogen burning. There is our philosoph-

ical candle. It is a foolish, feeble sort of a

flame, you may say, but it is so hot that scarcely

any common flame gives out so much heat. It

goes on burning regularly, and I am now about

to put that flame to burn under a certain ar-

rangement, in order that we may examine its

results and make use of the information which

we may thereby acquire. Inasmuch as the

PRODUCT OF COMBUSTION OF HYDROGEN. 89

candle produces water, and this gas comes out

of the water, let us see what this gives us by

the same process of combustion that the candle

went through when it burnt in the atmosphere,

and for that purpose I am going to put the

lamp under this apparatus, in order to condense

Fig. IS.

whatever may arise from the combustion within

it. In the course of a short time you will see

moisture appearing in the cylinder, and you

will get the water running down the side, and

the water from this hydrogen flame will have

absolutely the same effect upon all our tests,

being obtained by the same general process as

in the former case. This hydrogen is a very

beautiful substance. It is so lidit that it

90 ].IGHTNESS UF HYDROGEN.

carries things np; it is far lighter than the

atmosphere, and I dare say I can show you this

by an experiment which, if you are very clever,

some of you may even have skill enough to re-

peat. Here is our generator of hydrogen, and

here are some soap-suds. I have an India-

rubber tube connected with the hydrogen gen-

erator, and at the end of the tube is a tobacco-

pipe. I can thus put the pipe into the suds

and blow bubbles by means of the hydrogen.

You observe how the bubbles fall downward

when I blow them with my warm breath ; but

notice the difference when I blow them with

hj^drogen. [The lecturer here blew bubbles

with hydrogen, which rose to the roof of the

theatre.] It shows you how light this gas

must be in order to carry with it not merely

the ordinary soap-bubble, but the larger portion

of a drop hanging to the bottom of it. I can

show its lightness in a better way than this;

larger bubbles than these may be so lifted up;

indeed, in former times balloons used to be

filled with this gas. Mr. Anderson will fasten

this tube on to our generator, and we shall

have a stream of hydrogen here with which we

HYDROGEN BALLOONS. 91

can charge this balloon made of collodion. I

need not even be very careful to get all the air

out, for I know the power of this gas to carry

it up. [Two collodion balloons were inflated

and sent up, one being held by a string.] Here

is another larger one, made of thin membrane,

which we will fill and allow to ascend; you

will see they will all remain floating about

until the gas escapes.

What, then, are the comparative weights of

these substances? I have a table here which

will show you the proportion which their

weights bear to each other. I have taken a

pint and a cubic foot as the measures, and have

placed opposite to them the respective figures.

A pint measure of this hydrogen weighs three

quarters of our smallest weight, a grain, and a

cubic foot weighs one twelfth of an ounce;

whereas a pint of water weighs 8750 grains,

and a cubic foot of water weighs almost 1000

ounces. You see, therefore, what a vast dif-

ference there is between the weight of a cubic

foot of water and a cubic foot of hydrogen.

Hydrogen gives rise to no substance that can

become solid, either during combustion or after-

92 PRODUCT OF COMBUSTION OF HYDROGEN.

ward as a product of its combustion ; but when

it burns it produces water only;and if we take

a cold glass and put it over the flame, it be-

comes damp, and you have water produced im-

mediately in appreciable quantity ; and nothing

is produced by its combustion but the same

water which you have seen the flame of the

candle produce. It is important to remember

that this hydrogen is the only thing in nature

which furnishes water as the sole product of

combustion.

And now we must endeavor to find some

additional proof of the general character and

composition of water, and for this purpose I

will keep you a little longer, so that at our next

meeting we may be better prepared for the

subject. We have the power of arranging the

zinc which you have seen acting upon the water

by the assistance of an acid, in such a manner

as to cause all the power to be evolved in the

place where w^e require it. I have behind me

a voltaic pile, and I am just about to show you,

at the end of this lecture, its character and

power, that you may see what we shall have to

deal with when next we meet. I hold-here the

THE VOLTAIC BATTERY. 93

extremities of the wires which transport the

power from behind me, and which I shall cause

to act on the w^ater.

We have previously seen what a power of

combustion is j)bssessed by the potassium, or the

zinc, or the iron filings ; but none of them show

isuch energy as this. [The lecturer here made

contact between the two terminal wires of the

battery, when a brilliant flash of light was pro-

duced.] This light is, in fact, produced by a

forty-zinc power of burning ; it is a power that

I can carry about in my hands through these

wires at pleasure, although if I applied it

wrongly to myself it would destroy me in an

instant, for it is a most intense thing, and the

power you see here put forth while you count

five [bringing the poles in contact and exhibit-

ing the electric light] is equivalent to the

power of several thunder-storms, so great is its

force,(^*) And that you may see what intense

energy it has, I will take the ends of the wires

which convey the power from the battery, and

with it I dare say I can burn this iron file.

Kow this is a chemical power, and one which,

when we next meet, I shall apply to water, and

show you what results we are able to produce.

94 HYDROGEN.

LECTURE lY.

HYDROGEN" IN THE CANDLE. — BURNS INTO

WATER.— THE OTHER PART OF WATER.

—

OXYGEN.

I SEE you are not tired of the candle yet, or

I am sure you would not be interested in the

subject in the way you are. When our candle

was burning we found it produced water exact-

ly like the water we have around us ; and by

farther examination of this water we found in

it that curious body, hydrogen—that light sub-

stance of which there is some in this jar. Weafterward saw the burning powers of that hy-

drogen, and that it produced water. And I

think I introduced to your notice an apparatus

which I very briefly said was an arrangement

of chemical force, or power, or energy, so ad-

justed as to convey its power to us in these

wires ; and I said I should use that force to pull

the water to pieces, to see what else there was

in the water besides hydrogen ; because, you

ACTION OF NITRIC ACID ON COPPER. 95

remember, when we passed the water through

the iron tube, we by no means got the weight

of water back which we put in in the form of

steam, though we had a very large quantity of

gas evolved. We have now to see what is the

other substance present. That you may under-

stand the character and use of this instrument,

let us make an experiment or two. Let us put

together, first of all, some substances, knowing

what they are, and then see what that instru-

ment does to them. There is some copper (ob-

serve the various changes which it can under-

go), and here is some nitric acid, and you will

find that this, being a strong chemical agent,

will act very powerfully when I add it to the

copper. It is now sending forth a beautiful

red vapor ; but as we do not want that vapor,

Mr. Anderson will hold it near the chimney for

a short time, that we may have the use and

beauty of the experiment without the annoy-

ance. The copper which I have put into the

flask will dissolve : it will change the acid and

tlie water into a blue fluid containing copper

and other things, and I purpose then showing

you how this voltaic battery deals with it ; and

96 VOLTAIC DECOMPOSITION OF A SALT.

ill tlic mean time wc will arrange another kind

of experiment for you to see what power it lias.

This is a substance which is to us like water

—

that is to say, it contains bodies which we do

not know of as yet, as water contains a body

which we do not know as yet. Now this solu-

tion of a salt(^^) I will put upon paper and

spread about, and apply the power of the bat-

tery to it, and observe what will happen. Three

or four important things will happen which we

shall take advantage of. I place this wetted

paper upon a sheet of tin-foil, which is conven-

ient for keeping all clean, and also for the ad-

vantageous application of the power ; and this

solution, you see, is not at all affected by being

put upon the paper or tin-foil, nor by any thing

else I have brought in contact with it yet, and

which, therefore, is free to us to use as regards

that instrument. But first let us see that our

instrument is in order. Here are our wires.

Let us see whether it is in the state in which it

was last time. We can soon tell. As yet, when

I bring them together, we have no power, be-

cause the conveyers— what we call the elec-

trodes—the passages or ways for the electricity

VOLTAIC IGNITION OF PLATINUM. 97

—are stopped ; but now Mr. Anderson by that

[referring to a sudden flash at the ends of the

wires] has given me a telegram to say that it

is ready. Before I begin our experiment I will

get Mr. Anderson to break contact again at the

battery behind me, and we will put a platinum

wire across to connect the poles, and then if I

find I can ignite a pretty good length of this

wire we shall be safe in our experiment. Nowyou will see the power. [The connection was

established, and the intermediate wire became

red-hot.] There is the power running beauti-

fully through the wire, which I have made thin

on purpose to show you that we have those

powerful forces ; and now, having that power,

we will proceed with it to the examination of

water.

I have here two pieces of platinum, and if I

lay them down upon this piece of paper [the

moistened paper on the tin-foil] you will see no

action ; and if I take them up there is no change

that you can see, but the arrangement remains

just as it was before. But now see what hap-

pens : if I take these two poles and put either

one or the other of them down separately on

G

98 VOLTAIC DECOMPOSITION.

the platinum plates, they do nothing for me;

both are perfectly without action ; but if I let

them both be in contact at the same moment,

see what happens [a brown spot appeared under

each pole of the battery]. Look here at the

effect that takes place, and see how I have

pulled something apart from the white—some-

thing brown ; and I have no doubt, if I were

to arrange it thus, and were to put one of the

poles to the tin-foil on the other side of the

paper—why, I get such a beautiful action upon

the paper that I am going to see whether I

can not write with it—a telegram, if you please.

[The lecturer here traced the word '' juvenile"

on the paper with one of the terminal wires.]

See there how beautifully we can get our re-

sults.

You see we have here drawn something

which we have not known about before out of

this solution. Let us now take that flask from

Mr. Anderson's hands, and see what we can

draw out of that. This, you know, is a liquid

which we have j ust made up from copper and

nitric acid while our other experiments were

in hand ; and though I am making this experi-

REDUCTION OF COPPER. 99

ment very hastily, and may bungle a little, yet

I prefer to let you see what I do rather than

prepare it beforehand.

Now see what happens. These two platinum

plates are the two ends (or I will make them so

immediately) of this apparatus ; and I am about

to put them in contact with that solution, just

as we did a moment ago on the paper. It does

not matter to us whether the solution be on the

paper or whether it be in the jar, so long as we

bring the ends of the apparatus to it. If I put

the two platinums in by themselves they come

out as clean and as white as they go in [insert-

ing them into the fluid without connecting them

with the battery];but when we take the power

and lay that on [the platinums were connected

with the battery and again dipped into the

solution], this, you see [exhibiting one of the

platinums], is at once turned into copper, as it

were; it has become like a plate of copper;

and that [exhibiting the other piece of plati-

num] has come out quite clean. If I take

this coppered piece and change sides, the copper

will leave the right-hand side and come over to

the left side; what was before the coppered

100 DECOMPOSITION OF WATER.

plate comes out clean, and the plate which was

clean comes out coated with copper ; and thus

you see that the same copper we put into this

solution we can also take out of it by means of

this instrument.

Putting that solution aside, let us now see

what effect this instrument will have upon

water. Here are two little platinum plates

which I intend to make the ends of the battery,

and this (c) is a little vessel so shaped as to

enable me to take it to pieces, and show you its

construction. In these two cups (a and b) I

pour mercury, which touches the ends of the

wires connected with the platinum plates. In

the vessel (c) I pour some water containing a

little acid (but which is put in only for the pur-

pose of facilitating the action ; it undergoes no

change in the process), and connected with the

top of the vessel is a bent glass tube (d), which

may remind you of the pipe which was con-

nected with the gun-barrel in our furnace ex-

periment, and which now passes under the

jar (f). I have now adjusted this apparatus,

and we will proceed to affect the water in some

way or other. In the other case I sent the

DECOMPOSITION OF WATER. 101

water through a tube which was made red-hot

;

I am now going to pass the electricity through

the contents of this vessel. Perhaps I may boil

'

the water ; if I do boil the water I shall get

steam; and you know that steam condenses

when it gets cold, and you will therefore see by

that whether I do boil the water or not. Per-

iiaps, however, I shall not boil the water, but

produce some other effect. You shall have the

experiment and see. There is one wire which

I will put to this side (a), and here is the other

wire which I will put to the other side (b), and

you will soon see whether any disturbance takes

place. Here it is seeming to boil up famously

;

but does it boil? Let us see whether that

Firj. 19.

102 DECOMPOSITION OF WATER.

which goes out is steam or not. I think you

will soon see the jar (f) will be filled with

vapor, if that which rises from the water is

steam. But can it be steam ? Why, certainly

not; because there it remains, you see, un-

changed. There it is standing over the water,

and it can not therefore be steam, but must be a

permanent gas of some sort. What is it? Is

it hydrogen ? Is it any thing else ? AVell, we

will examine it. If it is hydrogen it will burn.

[The lecturer then ignited a portion of the gas

collected, which burnt with an explosion.] It

is certainly something combustible, but not com-

bustible in the way that hydrogen is. Hydro-

gen would not have given you that noise ; but

the color of that light, when the thing did

burn, was like that of hydrogen ; it will, how-

ever, burn without contact with the air. That

is why I have chosen this other form of appa-

ratus, for the purpose of pointing out to you

what are the particular circumstances of this

experiment. In place of an open vessel, I have

taken one that is closed (our battery is so

beautifully active that we are even boiling the

mercury, and getting all things right— not

SYNTHESIS OF WATER. 103

wrong, but vigorously right) ; and I am going

to show you that that gas, whatever it may be,

can burn without air, and in that respect dif-

fers from a candle, which can not burn with-

out the air. And our manner of doing this is

as follows: I have here a glass vessel (g)

which is fitted with two platinum wires (l k)

through which I can apply electricity ; and we

can put the vessel on the air-pump and exhaust

the air ; and when we have taken the air out

we can bring it here and fasten it on to this jar

(f), and let into the vessel that gas which was

formed by the action of the voltaic battery upon

the water, and which we have produced by

changing the water into it ; for I may go as

far as this, and say we have really, by that

experiment, changed the water into that gas.

We have not only altered its condition, but we

have changed it really and truly into that

gaseous substance, and all the water is there

which was decomposed by the experiment. As

I screw this vessel (a h) on here (h), and make

the tubes well connected, and when I open the

stop-cocks (h h h), if you watch the level of

the water (in f), you will see that the gas will

104: SYNTHESIS OF WATER.

rise. I willnow close the stop-cocks, as I have

drawn up as much as the vessel can hold, and

being safely conveyed into that chamber, I will

pass into it an electric spark from this Leyden

jar (l), when the vessel, which is now quite

clear and bright, will become dim. There will

be no sound, for the vessel is strong enough to

confine the explosion. [A spark was then

passed through the jar, when the explosive

mixture was ignited.] Did you see that bril-

liant light ? If I again screw the vessel on to

the jar, and open these stop-cocks, you will

see that the gas will rise a second time. [The

stop-cocks were then opened.] Those gases

[referring to the gases first collected in the jar,

and which had just been ignited by the electric

spark] have disappeared, as you see ; their place

is vacant, and fresh gas has gone in. Water has

been formed from them ; and if we repeat our

operation [repeating the last experiment], I

shall have another vacancy, as you will see by

the water rising. I always have an empty

vessel after the explosion, because the vapor or

gas into which that water has been resolved by

the battery explodes under the influence of the

DECOMPOSITION" OF WATER. 105

spark, and changes into water ; and by-and-by

you will see in this upper vessel some drops of'

water trickling down the sides and collecting

at the bottom.

We are here dealing with water entirely,

without reference to the atmosphere. The

water of the candle had the atmosphere helping

to produce it ; but in this way it can be pro-

duced independently of the air. Water, there-

fore, ought to contain that other substance

which the candle takes from the air, and which,

combining with the hydrogen, produces water.

Just now you saw that one end of this battery

took hold of the copper, extracting it from the

vessel which contained the blue solution. It

was effected by this wire ; and surely we maysay, if the battery has such power with a me-

tallic solution which we made and unmade,

may we not find that it is possible to split

asunder the component parts of the water, and

put them into this place and that place ? Sup-

pose I take the poles—the metallic ends of this

battery—and see what will happen with the

water in this apparatus (Fig. 20), where we have

separated the two ends far apart. I place one

106 r.::suLTS of decomposition of water.

here (at a), and the other there (at b) ;and I

have little shelves with holes which I can put

Fig. 20.

upon each pole, and so arrange them that

whatever escapes from the two ends of the

battery will appear as separate gases ; for you

saw that the water did not become vaporous,

but gaseous. The wires are now in perfect

and proper connection with the vessel contain-

ing the water, and you see the bubbles rising

;

let us collect these bubbles and see what they

are. Here is a glass cylinder (o) ; I fill it with

water and put it over one end (a) of the pile,

and I will take another (h), and put it over the

other end (b) of the pile. And so now we have

a double apparatus, with both places delivering

gas. Both these jars will fill with gas. There

HYDROGEN FROM WATER. 107

they go, that to the right (h) filling very

rapidl}^; the one to the left (o) filling not so

rapidly ; and, though I have allowed some

bubbles to escape, yet still the action is going

on pretty regularly ; and were it not that one is

rather smaller than the other, you would see

that I should have twice as much in this (h) as

I have in that (o). Both these gases are

colorless; they stand over the water without

condensing; they are alike in all things— I

mean in all apparent things ; and we have here

an opportunity of examining these bodies and

ascertaining what they are. Their bulk is large,

and we can easily apply experiments to them.

I will take this jar (h) first, and will ask you

to be prepared to recognize hydrogen.

Think of all its qualities— the light gas

which stood well in inverted vessels, burning

with a pale flame at the mouth of the jar, and

see whether this gas does not satisfy all these

conditions. If it be hydrogen it will remain

here while I hold this jar inverted. [A light

was then applied, when the hydrogen burnt.]

What is there now in the other jar? You know

that the two together made an explosive mix-

"108 OXYGEN FKOM WATER.

turc. But what can this be which we find as

the other constituent in water, and which must

therefore be that substance which made the

hydrogen burn ? We know that the water we

put into the vessel consisted of the two things

togethei-. We find one of these is hydrogen

:

what must that other be which was in the water

before the experiment, and which we now have

by itself? I am about to put this lighted

splinter of wood into the gas. The gas itself

will not burn, but it will make the splinter of

wood burn. [The lecturer ignited the end of

the wood and introduced it into the jar of gas.]

See how it invigorates the combustion of the

wood, and how it makes it burn far better than

the air would make it burn ; and now you see

by itself that every other substance which is

contained in the water, and which, when the

water was formed by the burning of the candle,

must have been taken from the atmosphere.

What shall we call it, A, B, or C ? Let us call

it O—call it "Oxygen;" it is a very good,

distinct-sounding name. This, then, is the ox-

ygen which was present in the water, forming

so large a part of it.

PREPARATION OF OXYGEN. 109

We shall now begin to understand more

clearly our experiments and researches, because

when we have examined these things once or

twice we shall soon see why a candle burns in

the air. When we have in this way analyzed

the water—that is to say, separated or electro-

lyzed its parts out of it, we get two volumes of

hydrogen and one of the body that burns it.

And these two are represented to us on the fol-

lowing diagram, with their weights also stated;

and we shall find that the oxygen is a very

heavy body by comparison with the hydrogen.

It is the other element in water.

Oxygen 88.9

Hydrogen 11.1

Water 100.0

I had better, perhaps, tell you now how we

get this oxygen abundantly, having shown you

how we can separate it from the water. Oxy-

gen, as you will immediately imagine, exists

in the atmosphere ; for how should the candle

burn to produce water without it? Such a

thing would be absolutely impossible, and chem-

ically impossible without oxygen. Can we

110 PREPARATION OF OXYGEN.

et it from the air ? Well, there are some veryo

complicated and difficult processes by which we

can get it from the air; but we have better

processes. There is a substance called the black

oxide of manganese ; it is a very black-looking

mineral, but very useful, and when made red-

hot it gives out oxygen. Here is an iron bottle

Fig. 21.

which has had some of this substance put into

it, and there is a tube fixed to it, and a fire

ready made, and Mr. Anderson will put that

retort into the fire, for it is made of iron, and

can stand the heat. Here is a salt called

chlorate of potassa, which is now made in large

quantities for bleaching, and chemical and med-

ical uses, and for pyrotechnic and other pur-

PREPARATION OF OXYGEN. Ill

poses. I will take some and mix it witli some

of the oxide of manganese (oxide of copper, or

oxide of iron would do as well), and if I put

tliese together in a retort, far less than a red

heat is sufficient to evolve this oxygen from the

mixture. I am not preparing to make much,

because we only want sufficient for our experi-

ments; only, as you will see immediately, if I

use too small a charge the first portion of the

gas will be mixed with the air already in the

retort, and I should be obliged to sacrifice the

first portion of the gas because it would be so

much diluted with air; the first portion must

therefore be thrown awa}^ You will find in

this case that a common spirit-lamp is quite

sufficient for me to get the oxygen, and so we

shall have two processes going on for its prep-

aration. See how freely the gas is coming

over from that small portion of the mixture.

We will examine it and see what are its prop-

erties. oSTow in this way w^e are producing,

as you will observe, a gas just like the one we

had in the experiment with the battery, trans-

parent, undissolved by water, and presenting

the ordinary visible properties of the atmos-

112 PROPERTIES OF OXYGEN.

phere. (As this first jar contains the air, to-

gether with the first portions of the oxygen set

free during the preparation, we will carry it

out of the way, and be prepared to make our

experiments in a regular, dignified manner.)

And inasmuch as that power of making wood,

wax, or other things burn, was so marked in

the oxygen we obtained by means of the voltaic

battery from water, we may expect to find the

same property here. We will try it. You see

there is the combustion of a lighted taper in

air, and here is its combustion in this gas

[lowering the taper into the jar]. See how

Fig. 22.

Q

brightly and how beautifully it burns ! You

can also see more than this : you will perceive

PROPERTIES OF OXYGEN. 113

it is a heavy gas, while the hydrogen would

go up like a balloon, or even faster than a

balloon, when not encumbered with the weight

of the envelope. You may easily see that al-

though we obtained from water twice as much

in volume of the hydrogen as of oxygen, it

does not follow that we have twice as much in

weight, because one is heavy and the other a

very light gas. We have means of weighing

gases or air ; but, without stopping to explain

that, let me just tell you what their respective

weights are. The weight of a pint of hydrogen

is three quarters of a grain ; the weight of the

same quantity of oxygen is nearly twelve

grains. This is a very great difference. The

weight of a cubic foot of hydrogen is one twelfth,

of an ounce ; and the weight of a cubic foot of

oxygen is one ounce and a third. And so on

we might come to masses of matter which may

be weighed in the balance, and which we can

take account of as to hundred-weights and as

to tons, as you will see almost immediately.

Now, as regards this very property of oxygen

supporting combustion, which we may compare

to air, I will take a piece of candle to show it

H

114 COMBUSTION OF A CANDLE IN OXYGEN.

you in a rough way— and the result will be

rough. There is our candle burning in the

air : how will it burn in oxj^gen ? I have here

a jar of this gas, and I am about to put it over

the candle for you to compare the action of this

gas with that of the air. Why, look at it ; it

looks something like the light you saw at the

poles of the voltaic battery. Think how vigor-

ous that action must be. And yet, during all

that action, nothing more is produced than what

is produced by the burning of the candle in

air. We have the same production of water,*

and the same phenomena exactly, when we use

this gas instead of air, as we have when the

candle is burnt in air.

But now we have got a knowledge of this

new substance, we can look at it a little more

distinctly, in order to satisfy ourselves that we

have got a good general understanding of this

part of the product of a candle. It is wonder-

ful how great the supporting powers of this

substance are as regards combustion. For in-

stance, here is a lamp which, simple though it

be, is the original, I may say, of a great vari-

ety of lamps which are constructed for divers

COMBUSTION OF A LAMP IN OXYGEN. 115

purposes— for light-houses, microscopic illu-

minations, and other uses; and if it was pro-

posed to make it burn very brightly, you

would say, " If a candle burnt better in oxy-

gen, will not a lamp do the same?" Why, it

will do so. Mr. Anderson will give me a tube

coming from our oxygen-reservoir, and I am

about to apply it to this flame, which I will

previously make burn badly on purpose. There

comes the oxygen: what a combustion that

makes I But if I shut it off, what becomes of

the lamp ? [The flow of oxygen was stopped,

and the lamp relapsed to its former dimness.]

It is wonderful how, by means of oxygen, we

get combustion accelerated. But it does not

affect merely the combustion of hydrogen, or

carbon, or the candle, but it exalts all com-

bustions of the common kind. We will take

one which relates to iron, for instance, as you

have already seen iron burn a little in the

atmosphere. Here is a jar of oxygen, and this

is a piece of iron wire ; but if it were a bar as

thick as my wrist, it would burn the same. I

first attach a little piece of wood to the iron ; I

then set the wood on fire, and let them both

116 IRON WIRE BURNED IN OXYGEN.

down together into tlie jar. The wood is now

alight, and there it burns as wood should burn

Fvj. 23.

in oxygen ; but it will soon communicate its

combustion to the iron. The iron is now burn-

ing brilliantly, and will continue so for a long

time. As long as we supply oxygen, so long

can we carry on the combustion of the iron,

until the latter is consumed.

We will now put that on one side, and take

some other substance ; but we must limit our

experiments, for we have not time to spare for

all the illustrations you would have a right to

if we had more time. "We will take a piece of

sulphur : you know how sulphur burns in the

air; well, we put it into the oxygen, and you

will see that whatever can burn in air can burn

with a far greater intensity in oxygen, leading

you to think that perhaps the atmosphere itself

SULPHUR BURNING IN OXYGEN. 117

owes all its power of combustion to this gas.

The sulphur is now burning very quietly in the

Fig. 24.

oxygen ; but you can not for a moment mistake

the very high and increased action which takes

place when it is so burnt, instead of being burnt

merely in common air.

I am now about to show you the combustion

of another substance— phosphorus. I can do

it better for you here than you can do it at

home. This is a very combustible substance

;

and if it be so combustible in air, what might

you expect it would be in oxygen ? I am about

to show it to you not in its fullest intensity, for

if I did so we should almost blow the apparatus

up ; I may even now crack the jar, though I do

not want to break things carelessly. You see

how it burns in the air. But what a glorious

118 PHOSPHORUS BURNING IN OXYGEN.

light it gives out when I introduce it into oxy-

gen ! [Introducing the lighted phosphorus

into the jar of oxygen.] There you see the

solid particles going off which cause that com-

bustion to be so brilliantly luminous.

Thus far we have tested this power of oxygen,

and the higli combustion it produces by means

of other substances. We must now, for a little

while longer, look at it as respects the hydro-

gen. You know, when we allowed the oxygen

and the hydrogen derived from the water to

mix and burn together, wc had a little explo-

sion. You remember also that when I burnt

the oxygen and the hydrogen in a jet together,

we got very little light, but great heat ; I am

now about to set fire to oxygen and hydrogen

mixed in the proportion in which they occur

in water. Here is a vessel containing one

volume of oxygen and two volumes of hydro-

gen. This mixture is exactly of the same na-

ture as the gas we just now obtained from the

voltaic battery ; it would be far too much to

burn at once; I have therefore arranged to

blow soap-bubbles with it and burn those

bubbles^ that we may see by a general experi-

COMBUSTION OF OXYGEN AND HYDROGEN. 119

ment or two how this oxygen supports the

combustion of the hydrogen. First of all we

will see whether we can blow a bubble. Well,

there goes the gas [causing it to issue through

a tobacco-pipe into some soap-suds]. Here I

have a bubble. I am receiving them on myhand, and you will perhaps think I am acting

oddly in this experiment, but it is to show you

that we must not always trust to noise and

sounds, but rather to real facts. [Exploding

a bubble on the palm of his hand.] I amafraid to fire a bubble from the end of the pipe,

because the explosion would pass up into the

jar and blow it to pieces. This oxygen, then,

will unite with the hydrogen, as you see by the

phenomena, and hear by the sound, with the

utmost readiness of action, and all its powers

are then taken up in its neutralization of the

qualities of the hydrogen.

So now I think you will perceive the whole

history of water with reference to oxygen and

the air from w^hat we have before said. Whydoes a piece of potassium decompose water?

Because it finds oxygen in the water. Whatis set free when I put it in the water, as I am

120 FORMATION OF WATER.

about to do again ? It sets free hydrogen, and

the hydrogen burns; but the potassium itself

combines with oxygen ; and this piece of po-

tassium, in taking the water apart—the water,

you may say, derived from the combustion of

the candle—takes away the oxygen which the

candle took from the air, and so sets the hydro-

gen free ; and even if I take a piece of ice, and

put a piece of potassium upon it, the beautiful

affinities by which the oxygen and the hydrogen

are related are such that the ice will absolutely

set fire to the potassium. I show this to you

to-day in order to enlarge your ideas of these

things, and that you may see how greatly results

are modified by circumstances. There is the

potassium on the ice, producing a sort of vol-

canic action.

It will be my place when next we meet, hav-

ing pointed out these anomalous actions, to show

you that none of these extra and strange ef-

fects are met with by us—that none of these

strange and injurious actions take place when

we are burning, not merely a candle, but gas

in our streets, or fuel in our fireplaces, so long

as we confine ourselves within the laws that

Nature has made for our guidance.

HYDROGEN AND OXYGEN. 121

LECTUEE Y.

OXYGEN PRESENT IN THE AIR.— NATURE OF

THE ATMOSPHERE.—ITS PROPERTIES.—OTH-

ER PRODUCTS FROM THE CANDLE.—CARBON-

IC ACID.—ITS PROPERTIES.

We have now seen that we can produce

hydrogen and oxygen from the water that we

obtained from the candle. Hydrogen, you

know, comes from the candle, and oxygen, you

believe, comes from the air. But then you

have a right to ask me, "How is it that the air

and the oxygen do not equally well burn the

candle?" If you remember what happened

when I put a jar of oxygen over a piece of

candle, you recollect there was a very different

kind of combustion to that which took place in

the air. Now why is this? It is a very im-

portant question, and one I shall endeavor to

make you understand; it relates most inti-

mately to the nature of the atmosphere, and is

most important to us.^

122 TESTS FOR OXYGEN".

We have several tests for oxygen besides tlie

mere burning of bodies;yon have seen a can-

dle burnt in oxygen or in the air; you have

seen phosphorus burnt in the air or in oxy-

gen, and you have seen iron filings burnt in

oxygen. But we have other tests besides these,

and I am about to refer to one or two of them

for the purpose of carrying your conviction and

your experience farther. Here we have a ves-

sel of oxygen. I will show its presence to

you : if I take a little spark and put it into that

oxygen, you know by the experience you gain-

ed the last time we met what will happen—if I

put that spark into the jar, it will tell you

whether we have oxygen here or not. Yes!

We have proved it by combustion ; and now

here is another test for oxygen, which is a very

curious and useful one. I have here two jars

full of gas, with a plate between them to pre-

vent their mixing ; I take the plate away, and

the gases are creeping one into the other.

"What happens?" say you; ''they together

produce no such, combustion as was seen in the

case of the candle." But see how the presence

of oxygen is told by its association witli this

TESTS FOR OXYGEN. 123

Other substance.('^) What a beautifully colored

gas I have obtained in this way, showing me

the presence of the oxygen ! In the same way

we can try this experiment by mixing common

air with this test-gas. Here is a jar containing

air—such air as the candle would burn in, and

here is a jar or bottle containing the test-gas.

I let them come together over water, and you

see the result : the contents of the test-bottle

are flowing into the jar of air, and you see I

obtain exactly the same kind of action as before,

and that shows me that there is oxygen in the

air—the very same substance that has been al-

ready obtained by us from the water produced

by the candle. But then, beyond that, how is

it that the candle does not burn in air as well

as in oxygen ? We wall come to that point at

once. I have here two jars; they are filled to

the same height with gas, and the appearance

to the eye is alike in both, and I really do not

know at present which of these jars contains

oxygen and which contains air, although I

know they have previously been filled with

these gases. But here is our test-gas, and I amgoing to work with the two jars, in order to

124 OXYGEN PRESENT IN THE AIR.

examine whether there is any difference between

them in the quahty of reddening this gas. I

am now going to turn this test-gas into one of

the jars, and observe what happens: There

is reddening, you see; there is, then, oxygen

present. We will now test the other jar; but

you see this is not so distinctly red as the first

;

and, farther, this curious thing happens : if I

take these two gases and shake them well to-

gether with water, we shall absorb the red

gas ; and then, if I put in more of this test-gas

and shake again, we shall absorb more ; and I

can go on as long as there be an}^ oxygen pres-

ent to produce that effect. If I let in air, it

will not matter; but the moment I introduce

water, the red gas disappears ; and I may go on

in this way, putting in more and more of the

test-gas, until I come to something left behind

which will not redden any longer by the use of

that particular body that rendered the air and

the oxygen red. Why is that ? You see in a

moment it is because there is, besides oxygen,

something else present which is left behind. I

will let a little more air into the jar, and if it

turns red you will know that some of that red-

NITROGEN IN THE AIR. 125

dening gas is still present, and that, consequent-

ly, it was not for the want of this producing

body that that air was left behind.

Now you will begin to understand what I

am about to say. You saw that when I burnt

phosphorus in a jar, as the smoke produced by

the phosphorus and the oxygen of the air con-

densed, it left a good deal of gas unburnt,just

as this red gas left something untouched

;

there was, in fact, this gas left behind, which

the phosphorus can not touch, which the red-

dening gas can not touch, and this something

is not oxygen, and yet is part of the atmos-

phere.

So that is one way of opening out air into

the two things of which it is composed—oxy-

gen, which burns our candles, our phosphorus,

or any thing else, and this other substance—nitrogen— which will not burn them. This

other part of the air is by far the larger pro-

portion, and it is a very curious body when we

come to examine it ; it is remarkably curious,

and yet you say, perhaps, that it is very unin-

teresting. It is uninteresting in some respects

because of this, that it shows no brilliant ef-

126 VALUE OF NITROGEN IN THE AIR.

fects of combustion. If I test it with a taper

as I do oxygen and hydrogen, it does not burn

like hydrogen, nor does it make the taper burn

like oxygen. Try it in any way I will, it does

neither the one thing nor the other; it will

not take fire ; it will not let the taper burn ; it

puts out the combustion of every thing. There

is nothing that will burn in it in common cir-

cumstances. It has no smell ; it is not sour; it

does not dissolve in water ; it is neither an acid

nor an alkali ; it is as indifferent to all our or-

gans as it is possible for a thing to be. Andyou might say, '' It is nothing; it is not worth

chemical attention ; what does it do in the air ?"

Ah! then come our beautiful and fine results

shown us by an observant philosophy. Sup-

pose, in place of having nitrogen, or nitrogen

and oxygen, we had pure oxygen as our atmos-

phere; what would become of us ? You know

very well that a piece of iron lit in a jar of ox-

ygen goes on burning to the end. When you

see a fire in an iron grate, imagine where the

grate would go to if the whole of the atmos-

phere were oxygen. The grate would burn up

more powerfully than the coals ; for the iron of

PROPERTIES OF NITROGEN. 127

the grate itself is even more combustible than

the coals which we burn in it. A fire put into

the middle of a locomotive would be a fire in

a magazine of fuel, if the atmosphere were oxy-

gen. The nitrogen lowers it down and makes

it moderate and useful for us, and then, with

all that, it takes away with it the fumes that

you have seen produced from the candle, dis-

perses them throughout the whole of the at-

mosphere, and carries them away to places

where they are wanted to perform a great and

glorious purpose of good to man, for the suste-

nance of vegetation, and thus does a most

wonderful work, although you say, on examin-

ing it, "Why, it is a perfectly indifferent thing."

This nitrogen in its ordinary state is an inactive

element; no action short of the most intense

electric force, and then in the most infinitely

small degree, can cause the nitrogen to com-

bine directly with the other element of the at-

mosphere, or with other things round about it

;

it is a perfectly indifferent, and therefore to say,

a safe substance.

But, before I take you to that result, I must

tell you about the atmosphere itself. I have

128 COMPOSITION OF THE ATMOSPHERE.

written on this diagram the composition of one

hundred parts of atmospheric air

:

Bulk. Weight.

Oxygen 20 23.3

Nitrogen ._80 77.7

100 100.0

It is a true analysis of the atmosphere so far as

regards the quantity of oxygen and the quanti-

ty of nitrogen present. By our analysis, we find

that 5 pints of the atmosphere contain only 1

pint of oxygen, and 4 pints, or 4 parts, of ni-

trogen by bulk. That is our analysis of the

atmosphere. It requires all that quantity of

nitrogen to reduce the oxygen down, so as to be

able to supply the candle properly with fuel, so

as to supply us with an atmosphere which our

lungs can healthily and safely breathe ; for it is

just as important to make the oxygen right for

us to breathe, as it is to make the atmosphere

right for the burning of the fire and the candle.

But now for this atmosphere. First of all,

let me tell you the weight of these gases. Apint of nitrogen weighs IOt^ grains, or a cubic

foot weighs 1^ ounces. That is the weight of

the nitrogen. The oxygen is heavier: a pint

of it weighs llfV grs., and a cubic foot weighs

METHOD OF WEIGHING GASES. 12^

If oz. A pint of air weighs about lOyV g^'s.,

and a cubic foot li oz.

You have asked me several times, and I am

very glad you have, "How do you weigh

gases?" I will show you: it is very simple,

and easily done. Here is a balance, and here a

copper bottle made as light as we can consistent

with due strength, turned very nicely in the

lathe, and made perfectly air-tight, with a stop-

cock, which we can open and shut, which at

Fig. 25.

130 METHOD OF WEIGHING GASES.

present is open, and, therefore, allows the bottle

to be full of air. I have here a nicely-adjusted

balance in which I think the bottle, in its pres-

ent condition, will be balanced by the weight

on the other side. And here is a pump by

which we can force the air into this bottle, and

with it we will force in a certain number of

volumes of air as measured by the pump.

[Twenty measures were pumped in.] We will

shut that in and put it in the balance. See

how it sinks; it is much heavier than it was.

By what ? By the air that we have forced into

it by the pump. There is not a greater hulk of

air, but there is the same bulk of heavier air,

because we have forced in air upon it. Andthat you may have a fair notion in your mind

as to how much this air measures, here is a jar

full of water. We will open that copper vessel

into this jar, and let the air return to its former

state. All I have to do now is to screw them

tightly together, and to turn the taps, when

there, you see, is the bulk of the twenty pumps

of air w^hich I forced into the bottle ; and to

make sure that we have been quite correct in

what we have been doing, we will take the

METHOD OF WEIGHING GASES. 131

bottle again to the balance, and if it is now

counterpoised by the original weight, we shall

Fig. 2G.

be quite sure we have made our experiment

correctly. It is balanced ; so, you see, we can

find out the weight of the extra volumes of air

forced in in that way, and by that means we are

able to ascertain that a cubic foot of air weighs

li- oz. But that small experiment will by no

means convey to your mind the whole literal

truth of this matter. It is wonderful how it

accumulates when you come to larger volumes.

132 WEIGHT OF THE ATMOSPHERE.

This bulk of air [a cubic foot] weighs 1^ oz.

What do you think of the contents of that box

above there which I have had made for the

purpose? The air which is within that box

weighs one pound—a full pound; and I have

calculated the weight of the air in this room:

you would hardly imagine it, but it is above a

ton. So rapidly do the weights rise up, and so

important is the presence of the atmosphere,

and of the oxygen and the nitrogen in it, and

the use it performs in conveying things to and

fro from place to place, and carrying bad va-

pors to places where they will do good instead

of harm.

Having given you that little illustration with

respect to the weight of the air, let me show

you certain consequences of it. You have a

right to them, because you would not under-

stand so much without it. Do you remember

this kind of experiment ? have you ever seen

it ? Suppose I take a pump somewhat similar

to the one I had a little while ago to force air

into the bottle, and suppose I place it in such

a manner that by certain arrangements I can

apply my hand to it. My hand moves about

WEIGHT OF THE ATMOSPHERE. 133

in the air so easily that it seems to feel nothing,

and I can hardly get velocity enough by any

motion of my own in the atmosphere to make

sure that there is much resistance to it. But

when I put my hand here [on the air-pump re-

Fig. 27.

ceiver, which was afterward exhausted] you

see what happens. Why is my hand fastened

to this place, and why am I able to pull this

pump about? And see! how is it that I can

hardly get my hand away ? Why is this ? It

is the weight of the air—the weight of the air

that is above. I have another experiment here,

which I think will explain to you more about

it. When the air is pumped from underneath

the bladder which is stretched over this glass,

you will see the effect in another shape :the

top is quite flat at present, but I will make a

very little motion with the pump, and now look

134 WEIGHT OF THE ATMOSPHERE.

at it ; see how it has gone down ; see how it is

bent in;you will see the bladder go in more

and more, until, at last, I expect it will be

driven in and broken by the force of the at-

mosphere pressing upon it [the bladder, at last,

broke with a loud report]. Now that was done

entirely by the weight of the air pressing on it,

and you can easily understand how that is.

The particles that are piled up in the atmos-

phere stand upon each other, as these five cubes

do;you can easily conceive that four of these

five cubes are resting upon the bottom one, and

Fig. 28,

if I take that away the others will all sink

down. So it is with the atmosphere ; the air

WEIGHT OF THE ATMOSPHERE. 185

that is above is sustained by the air that is be-

neath, and when the air is pumped away from

beneath them, the change occurs which you saw

when I placed my hand on the air-pump, and

which you saw in the case of the bladder, and

which you shall see better here. I have tied

over this jar a piece of sheet India-rubber, and

I am now about to take away the air from the

inside of the jar ; and if you will watch the In-

dia-rubber—which acts as a partition between

the air below and the air above—^you will see,

when I pump, how the pressure shows itself.

See where it is going to : I can actually put myhand into the jar ; and yet this result is only

caused by the great and powerful action of the

air above. How beautifully it shows this cu-

rious circumstance

!

Here is something that you can have a pull

at when I have finished to-day. It is a little

apparatus of two hollow brass hemispheres,

closely fitted together, and having connected

with it a pipe and a cock, through which we

san exhaust the air from the inside ; and al-

though the two halves are so easily taken

apart while the air is left within, yet you will

136 THE SUCKER.

see, wlicn we exhaust it by-and-by, no power

of any two of you will be able to pull them

apart. Every square inch of surface that is

contained in the area of that vessel sustains fif-

teen pounds by weight, or nearly so, when the

air is taken out, and you may try your strength

presently in seeing whether you can overcome

that pressure of the atmosphere.

Here is another very pretty thing—the hoy. '

sucker, only refined by the philosopher. Weyoung ones have a perfect right to take toys,

and make them into philosophy, inasmuch as

nowadays we are turning philosophy into toys.

Here is a sucker, only it is made of India-rub-

ber. If I clap it upon the table, you see at

once it holds. Why does it hold ? I can slip

it about, and yet if I try to pull it up, it seems

as if it would pull the table with it. I can

easily make it slip about from place to place,

but only when I bring it to the edge of the ta-

ble can I -get it off. It is only kept down by

the pressure of the atmosphere above ; we have

a couple of them, and if you take these two and

press them together, you will see how firmly

-they stick. And, indeed, we may use them as

PRESSURE OF THE ATMOSPHERE. 137

tliey are proposed to be used, to stick against

windows or against walls, where they will

adhere for an evening, and serve to hang any

thing on that you want. I think, however,

that you boys ought to be shown experiments

that you can make at home ; and so here is a

very pretty experiment in illustration of the

pressure of the atmosphere. Here is a tumbler

of water. Suppose I were to ask you to turn

that tumbler upside down so that the water

should not fall out, and yet not be kept in by

your hand, but merely by using the pressure of

the atmosphere; could you do that? Take a

wine-glass, either quite full or half full of water,

and put a flat card on the top ; turn it upside

down, and then see what becomes of the card

and of the water. The air can not get in be-

cause the water, by its capillary attraction

round the edge, keeps it out.

I think this will give you a correct notion of

what you may call the materiality of the air;

and when I tell you that that box holds a pound

of it, and this room more than a ton, you will

begin to think that air is something very

serious. I will make another experiment to

138 THE POPGUN.

convince joii of this positive resistance. There

is that beautiful experiment of the popgun,

made so well and so easily, you know, out of a

quill, or a tube, or any thing of that kind;

where we take a slice of potato, for instance, or

an apple, and take the tube and cut out a pellet,

as I have now done, and push it to one end. I

have made that end tight ; and now I take an-

other piece and put in : it will confine the air

that is within the tube perfectly and completely

for our purpose ; and I shall now find it abso-

lutely impossible by any force of mine to drive

that little pellet close up to the other. It can

not be done ; I may press the air to a certain

extent, but if I go on pressing, long before it

comes to the second the confined air will drive

the front one out with a force something like

that of gunpowder; for gunpowder is in part

dependent upon the same action that you see

here exemplified.

I saw the other day an experiment which

pleased me much, as I thought it would serve

our purpose here. (I ought to have held my

tongue for four or five minutes before beginning

this experiment, because it depends upon my

COMPKESSIBILITY OF AIR. 139

lungs for success.) By the proper application

of air, I expect to be able to drive this egg out

of one cup into the other by the force of mybreath ; but if I fail it is in a good cause, and I

do not promise success, because I have been

talking more than I ought to do to make the

experiment succeed.

[The lecturer here tried the experiment, and

succeeded in blowing the egg from one egg-cup

to the other.]

You see that the air which I blow goes down-

ward between the egg and the cup, and makes

a blast under the egg, and is thus able to lift a

heavy thing; for a full egg is a very heavy

thing for air to lift. If you want to make the

experiment, you had better boil the egg quite

hard first, and then you may very safely try to

blow it from one cup to the other with a little

care.

I have now kept you long enough upon this

property of the weight of the air, but there is

another thing I should like to mention. Yousaw the way in which, in this popgun, I was

able to drive the second piece of potato half or

two thirds of an inch before the first piece

:14:0 ELASTICITY OF AIR.

started, b}^ virtue of the elasticity of the air,

just as I pressed into the copper bottle the

particles of air by means of the pump. Nowthis depends upon a wonderful property in the

air, namely, its elasticity, and I should like to

give you a good illustration of this. If I take

any thing that confines the air properly, as this

membrane, which also is able to contract and

expand so as to give us a measure of the elas-

ticity of the air, and confine in this bladder a

certain portion of air; and then, if we take

the atmosphere off from the outside of it, just as

in these cases we put the pressure on— if we

take the pressure off, you will see how it will

then go on expanding and expanding, larger

and larger, until it will fill the whole of this

bell-jar, showing you that wonderful property

of the air, its elasticity, its compressibility, and

expansibility, to an exceedingly large extent,

and which is very essential for the purposes

and services it performs in the economy of

creation.

We will now turn to another very important

part of our subject, remembering that we have

examined the candle in its burning, and have

OTHER PRODUCTS FROM THE CANDLE. 141

found that it gives rise to various products.

"We have the ^^roducts, you know, of soot, of

water, and of something else, which you have

not yet examined. We have collected the

water, but have allowed the other things to go

into the air. Let us now examine some of

these other products.

Here is an experiment which I think will

help you in part in this way. We will put our

candle there, and place over it a chimney, thus.

I think my candle will go on burning, because

the air-passage is open at the bottom and the

top. In the first place, you see the moisture

appearing—that you know about. It is water

produced from the candle by the action of the

air upon its hydrogen. But, besides that, some-

thing is going out at the top : it is not moist-

ure— it is not water— it is not condensible

;

and yet, after all, it has very singular proper-

ties. You will find that the air coming out of

the top of our chimney is nearly sufficient to

blow the light out I am holding to it ; and if I

put the light fairly opposed to the current, it

will blow it quite out. You will say, that is as

it should be, and I am supposing that you think

142 OTHER PRODUCTS FROM TPIE CANDLE.

it ought to do so, because tlie nitrogen does not

support combustion, and ought to put the can-

Fig. 29.

die out, since the candle will not burn in nitro-

gen. But is there nothing else there than ni-

trogen ? I must now anticipate—that is to say,

I must use my own knowledge to supply you

with the means that we adopt for the purpose

of ascertaining these things, and examining

such gases as these. I will take an empty bot-

tle— here is one— and if I hold it over this

chimney, I shall get the combustion of the can-

dle below sendinpr its results into the bottle

GASEOUS PRODUCTS OF COMBUSTION. 143

above ; and we shall soon find that this bottle

contains not merely an air that is bad as regards

the combustion of a taper put into it, but hav-

ing other properties.

Let me take a little quick-lime and pour

some common water on to it— the commonest

water Y>^ill do. I will stir it a moment, then

pour it upon a piece of filtering paper in a fun-

nel, and we shall very quickly have a clear

water proceeding to the bottle below, as I have

here. I have plenty of this water in another

bottle, but nevertheless I should like to use the

lime-water that was prepared before you, so

that you may see what its uses are. If I take

some of this beautiful clear lime-water, and

pour it into this jar which has collected the air

from the candle, you will see a change coming

about. Do you see that the water has become

quite milky ? Observe, that will not happen

with air merely. Here is a bottle filled with

air; and if I put a little lime-water into it,

neither the oxygen nor the nitrogen, nor any

thing else that is in that quantity of air, will

make any change in the lime-water ; it remains

perfectly clear, and no shaking of that quantity

144 PROPERTIES OF THE NEW GAS.

of lime-water with that quantity of air in its

common state will cause any change ; but if I

take this bottle with the lime-water and hold it

so as to get the general products of the candle

in contact with it, in a very short time we shall

have it milky ; there is the chalk, consisting of

the lime which we used in making the lime-

water, combined with something that came

from the candle—that other product which we

are in search of, and which I want to tell you

about to-day. This is a substance made visible

to us by its action, which is not the action of

the lime-water either upon the oxygen or upon

the nitrogen, nor upon the water itself, but it

is something new to us from the candle. And

then we find this white powder, produced by

the lime-water and the vapor from the candle,

appears to us very much like whitening or

chalk, and when examined it does prove to be

exactly the same substance as whitening or

chalk. So we are led, or have been led, to ob-

serve upon the various circumstances of this

experiment, and to trace this production of

chalk to its various causes, to give us the true

knowledge of the nature of this combustion of

CARBONIC ACID FROM THE CANDLE. 145

the candle—to find that this substance issuing

from the candle is exactly the same as that

substance which would issue from a retort if I

were to put some chalk into it wnth a little

moisture and make it red-hot;you would then

find that exactly the same substance would is-

sue from it as from the candle.

But we have a better means of getting this

substance, and in greater quantity, so as to as-

certain what its general characters are. Wefind this substance in very great abundance in

a multitude of cases where you would least ex-

pect it. All limestones contain a great deal

of this gas which issues from the candle, and

which we call carbonic acid. All chalks, all

shells, all corals, contain a great quantity of

this curious air. We find it fixed in these

stones, for which reason Dr. Black called it

"fixed air"—finding it in these fixed things like

marble and chalk— he called it fixed air be-

cause it lost its quality of air, and assumed the

condition of a solid body. We can easily get

this air from marble. Here is a jar containing

a little muriatic acid, and here is a taper which,

if I put it into that jar, will show only the pres-

K

146 CARBONIC ACID FROM OTHER SOURCES.

ence of common a-ir. There is, you see, pure

air down to the bottom ; the jar is full of it.

Here is a substance—marble(^')—a very beau-

tiful and superior marble ; and if I put these

pieces of marble into the jar, a great boiling ap-

parently goes on. That, however, is not steam;

it is a gas that is rising up ; and if I now search

the jar by a candle, I shall have exactly the

same effect produced upon the taper as I had

from the air which issued from the end of the

chimney over the burning candle. It is exact-

ly the same action, and caused by the very same

substance that issued from the candle ; and in

this way we can get carbonic acid in great

abundance—we have already nearly filled the

jar. We also find that this gas is not merely

contained in marble. Here is a vessel in which

I have put some common whitening— chalk

which has been washed in water and deprived

of its coarser particles, and so supplied to the

plasterer as whitening—here is a large jar con-

taining this whitening and water ; and I have

here some strong sulphuric acid, which is the

acid you might have to use if you were to make

these experiments (only, in using this acid with

PREPARATION OF CARBONIC ACID. 147

limestone, the body that is iDroduced is an in-

soluble substance, wliereas the muriatic acid

produces a soluble substance that does not so

much thicken the water). And you will seek

out a reason why I take this kind of apparatus

for the purpose of showing this experiment.

I do it because you may repeat in a small way

what I am about to do in a large one. Youwill have here just the same kind of action ; and

I am evolving in this large jar carbonic acid

exactly the same in its nature and properties as

the gas which we obtained from the combus-

tion of the candle in the atmosphere. And, no

matter how different the two methods by which

we prepare this carbonic acid, you will see,

when we get to the end of our subject, that it

is all exactly the same, whether prepared in

the one way or in the other.

We will now proceed to the next experiment

with regard to this gas. What is its nature?

nere is one of the vessels full, and we will try

it as we have done so many other gases— by

combustion. You see it is not combustible, nor

does it support combustion. ISTeither, as we

know, does it dissolve much in water, because

14.8 CARBONIC ACID SOLUBLE IN WATER.

we collect it over water very easily. Then you

know that it has an effect, and becomes white

in contact with lime-water; and when it does

become white in that way, it becomes one of

the constituents to make carbonate of lime or

limestone.

The next thing I must show you is that it

really does dissolve a little in water, and there-

fore that it is unlike oxj^gen and hydrogen in

that respect. I have here an apparatus by

which we can produce this solution. In the

lower part of this apparatus is marble and acid,

and in the upper part cold water. The valves

are so arranged that the gas can get from one

to the other. I will set it in action now, and

you can see the gas bubbling up through the

water, as it has been doing all night long, and

by this time we shall fmd that we have this

substance dissolved in the water. If I take a

glass and draw off some of the water, I fmd

that it tastes a little acid to the mouth ; it is

impregnated with carbonic acid ; and if I now

apply a little lime-water to it, that will give us

a test of its presence. This water will make

the lime-water turbid and white, which is proof

of the presence of carbonic acid.

DENSITY OF CARBONIC ACID. 140

Then it is a very weighty gas ; it is heavier

than, the atmosphere. I have put their respect-

ive weights at the lower part of this table,

along with, for comparison, the weights of the

other gases we have been examining

:

'

Pint. Cubic FooL

Hydrogen f grs. t^ oz-

Oxygen U^ 1^

Nitrogen 10^^ 11

Air 10^1, 1-1-

Carbonic acid IG^ 1-^

A pint of it weighs 16^ grs., and a cubic foot

weighs l-i-^^ oz., almost two ounces. You can

see by many experiments that this is a heavy

gas. Suppose I take a glass containing nothing

else but air, and from this vessel containing

the carbonic acid I attempt to pour a little of

this gas into that glass—I wonder whether any

has gone in or not. I can not tell by the ap-

pearance, but I can in this way [introducing

the taper]. Yes, there it is, you see; and if I

were to examine it by lime-water, I should find

it by that test also. I will take this little

bucket, and put it down into the well of car-

bonic acid— indeed, we too often have real

wells of carbonic acid—and now, if there is any

150 DENSITY OF CARBONIC ACID.

carbonic acid, I must have got to it by this

time, and it will be in this bucket, which we

Fig. 30.

will examine with a taper. There it is, you

see ; it is full of carbonic acid.

There is another experiment by which I will

show you its weight. I have here a jar sus-

pended at one end of a balance—it is now equi-

poised ; but when I pour this carbonic acid into

the jar on the one side which now contains air,

you will see it sink down at once because of

the carbonic acid that I pour into it. And

now, if I examine this jar with the lighted ta-

per, I shall find that the carbonic acid has fallen

DENSITY OF CARBONIC ACID. 151

into it, and it no longer has any power of sup-

porting the combustion. If I blow a soap-bub-

Fig. 31.

ble, which of course will be filled wdth air, and

let it fall into this jar of carbonic acid, it will

float. But I shall first of all take one of these

little balloons filled with air. I am not quite

sure where the carbonic acid is; w^e will just

try the depth, and see whereabouts is its level.

There, you see, we have this bladder floating

on the carbonic acid; and if I evolve some

more of the carbonic acid, the bladder will be

lifted up higher. There it goes; the jar is

nearly full, and now I will see whether I can

blow a soap-bubble on that and float it in the

same way. [The lecturer here blew a soap-

bubble and allowed it to fall into the jar of

152 DENSITY OF CARBONIC ACID.

carbonic acid, when it floated in it midway.]

It is floating as the balloon floated by virtue of

the greater weight of the carbonic acid than of

the air. And now, having so far given you

the history of the carbonic acid, as to its sources

in the candle, as to its physical properties and

weight, when we next meet I shall show you

of what it is composed, and where it gets its

elements from.

CANDLES FROM JAPAN. 153

LECTUEE YL

CARBON OR CHARCOAL.—COAL-GAS.—RESPIRA-

TION AND ITS ANALOGY TO THE BURNING

OF A CANDLE.—CONCLUSION.

A LADY who honors me by her presence at

these lectures has conferred a still farther obli-

gation by sending me these two candles, which

are from Japan, and, I presume, are made of

that substance to which I referred in a former

lecture. You see that they are even far more

highly ornamented than the French candles,

and, I suppose, are candles of luxur\^, judging

from their appearance. They have a remark-

able peculiarity about them, namely, a hollow

wick—that beautiful peculiarity which Argand

introduced into the lamp and made so valuable.

To those who receive such presents from the

East, I may just say that this and such like

materials gradually undergo a change which

gives them on the surface a dull and dead ap-

pearance; but they may easily be restored to

154 CARBONIC ACID.

their original beauty if the surface be rubbed

with a clean cloth or silk handkerchief, so as

to polish the little rugosity or roughness : this

will restore the beauty of the colors. I have

so rubbed one of these candles, and you see the

difference between it and the other which has

not been polished, but which may be restored

by the same process. Observe, also, that these

moulded candles from Japan are made more

conical than the moulded candles in this part

of the world.

I told you, when we last met, a good deal

about carbonic acid. We found by the lime-

water test that when the vapor from the top

of the candle or lamp was received into bottles

and tested by this solution of lime-water (the

composition of which I explained to you, and

which you can make for yourselves), we had

that white opacity which was in fact calcareous

matter, like shells and corals, and many of the

rocks and minerals in the earth. But I have

not yet told you fully and clearly the chemical

history of this substance, carbonic acid, as we

have it from the candle, and I must now resume

that subject. We have seen the products, and

CARBON IN CARBONIC ACID. 155

tbe nature of them, as they issue from the can-

dle. We have traced the water to its elements,

and now we have to see where are the ele-

ments of the carbonic acid supplied by the can-

dle : a few experiments will show this. You

remember that when a candle burns badly it

produces smoke ; but if it is burning well,

there is no smoke. And you know that the

brightness of the candle is due to this smoke,

which becomes ignited. Here is an experiment

to prove this : so long as the smoke remains in

the flame of the candle and becomes ignited, it

gives a beautiful light, and never appears to

us in the form of black particles. I will light

some fuel which is extravagant in its burning

:

this will serve our purpose—a little turpentine

on a sponge. You see the smoke rising from

it, and floating into the air in large quantities

;

and remember now, the carbonic acid that we

have from the candle is from such smoke as

that. To make that evident to you, I will in-

troduce this turpentine burning on the sponge

into a flask where I have plenty of oxygen, the

rich part of the atmosphere, and you now see

that the smoke is all consumed. This is the

156 FORMATION" OF CARBONIC ACID.

first part of our experiment ; and now what fol-

lows? The carbon which you saw flying off

from the turpentine flame in the air is now en-

tirely burned in this oxygen, and we shall find

that it will, by this rough and temporary ex-

periment, give us exactly the same conclusion

and result as we had from the combustion of

the candle. The reason why I make the ex-

periment in this manner is solely that I maycause the steps of our demonstration to be so

simple that you can never for a moment lose

the train of reasoning, ifyou only pay attention.

All the carbon which is burned in oxygen, or

air, comes out as carbonic acid, while those par-

ticles which are not so burned show you the

second substance in the carbonic acid, namely,

the carbon—that body which made the flame

so bright while there was plenty of air, but

which was thrown off in excess when there was

not oxygen enough to burn it.

I have also to show you a little more dis-

tinctly the history of carbon and oxygen in

their union to make carbonic acid. You are

now better able to understand this than before,

and I have prepared three or four experiments

COMBUSTION OF CARBOX. 157

by way of illustration. This jar is filled with

oxygen, and here is some carbon which has

been placed in a crucible for the purpose of be-

ing made red-hot. I keep my jar dry, and ven-

ture to give you a result imperfect in some de-

gree, in order that I may make the experiment

brighter. I am about to put the oxygen and

the carbon together. That this is carbon (com-

mon charcoal pulverized) you will see by the

way in which it burns in the air [letting some

of the red-hot charcoal fall out of the cruci-

ble], I am now about to burn it in oxygen

gas, and look at the difference. It may appear

to you at a distance as if it were burning with

a flame ; but it is not so. Every little piece of

charcoal is burning as a spark, and while it so

burns it is producing carbonic acid. I special-

ly want these two or three experiments to point

out what I shall dwell upon more distinctly

by-and-by—that carbon burns in this way, and

not as a flame.

Instead of taking many particles of carbon

to burn I will take a rather large piece, which

will enable 3^ou to see the form and size, and to

trace the effects very decidedly. Here is the

158 CARBON BURNS WITH A SPARK.

jar of oxygen, and here is the piece of charcoal,

to which I have fastened a little piece of wood,

which I can set fire to, and so commence the

combustion, which I could not conveniently do

without. You now see the charcoal burning,

but not as a flame (or if there be a flame it is

the smallest possible one, which I know the

cause of, namely, the formation of a little car-

bonic oxide close upon the surface of the car-

bon). It goes on burning, you see, slowly pro-

ducing carbonic acid by the union of this car-

bon or charcoal (they are equivalent terms) with

the oxygen. I have here another piece of

charcoal, a piece of bark, w^hich has the quality

of being blown to pieces— exploding— as it

burns. By the effect of the heat we shall re-

duce the lump of carbon into particles that will

fly off; still every particle, equally with the

whole mass, burns in this peculiar way— it

burns as a coal and not like a flame. You ob-

serve a multitude of little combustions going

on, but no flame. I do not know a finer ex-

periment than this to show that carbon burns

with a spark.

Here, then, is carbonic acid formed from its

COMPOSITION OF CARBONIC ACID. 159

elements. It is produced at once; and if avc

examined it by lime-water, you will sec that

we have the same substance which I have pre-

viously described to you. By putting together

() parts of carbon by weight (whether it comes

from the flame of a candle or from powdered

charcoal) and 16 parts of oxygen by weight,

we have 22 parts of carbonic acid ; and, as we

saw last time, the 22 parts of carbonic acid

combined with 28 parts of lime, produced

common carbonate of lime. If you were to

examine an oyster-shell and weigh the com-

ponent parts, you would find that every 60

parts would give 6 of carbon and 16 of oxygen

combined with 28 of lime. However, I do not

want to trouble you with these minutiae ; it is

only the general philosophy of the matter that

we can now go into. See how finely the carbon

is dissolving away [pointing to the lump of

charcoal burning quietly in the jar of oxygen].

You may say that the charcoal is actually dis-

solving in the air round about ; and if that were

perfectly pure charcoal, which we can easily

prepare, there would be no residue whatever.

When we have a perfectly cleansed and purified

IGO ANALYSIS OF CARBONIC ACID.

piece of carbon, there is no ash left. The car-

bon burns as a solid dense body, that heat alone

can not change as to its solidity, and yet it

passes away into vapor that never condenses

into solid or liquid under ordinary circum-

stances; and what is more curious still is the

fact that the oxygen does not change in its

bulk by the solution of the carbon in it. Just

as the bulk is at first, so it is at last, only it has

become carbonic acid.

There is another experiment which I must

give you before you are fully acquainted with

the general nature of carbonic acid. Being a

compound body, consisting of carbon and ox-

ygen, carbonic acid is a body that we ought to

be able to take asunder. And so we can. As

we did with water, so we can with carbonic

acid— take the two parts asunder. The sim-

plest and quickest way is to act upon the car-

bonic acid by a substance that can attract the

oxygen from it, and leave the carbon behind.

You recollect that I took potassium and put it

upon water or ice, and you saw that it could

take the oxygen from the hydrogen. Now,

suppose we do something of the same kind here

ANALYSIS OF CARBONIC ACID. 161

with this carbonic acid. You know carbonic

acid to be a heavy gas : I will not test it with

lime-water, as that will interfere with our sub-

sequent experiments, but I think the heaviness

of the gas and the power of extinguishing

flame will be sufficient for our purpose. I in-

troduce a flame into the gas, and you will see

whether it will be put out. You see the light

is extinguished. Indeed, the gas may, perhaps,

put out phosphorus, which you know has a

pretty strong combustion. Here is a piece of

phosphorus heated to a high degree. I intro-

duce it into gas, and you observe the light is

put out, but it will take fire again in the air,

because there it re-enters into combustion.

Now let me take a piece of potassium, a sub-

stance which even at common temperatures can

act upon carbonic acid, though not sufficiently

for our present purpose, because it soon gets

covered with a protecting coat ; but if we warm

it up to the burning point in air, as we have a

fair right to do, and as we have done with

phosphorus, you will see that it can burn in

carbonic acid ; and if it burns, it will burn by

taking oxygen, so that you will see what is left

L

162 CARBON FROM CARBONIC ACID.

behind. I am going, then, to burn this potas-

sium in the carbonic acid, as a proof of the ex-

istence of oxygen in the carbonic acid. [In the

preliminary process of heating the potassium

exploded.] Sometimes we get an awkward

piece of potassium that explodes, or something

like it, when it burns. I will take another

piece, and now that it is heated I introduce it

into the jar, and you perceive that it burns in

the carbonic acid— not so well as in the air,

because the carbonic acid contains the oxygen

combined ; but it does burn, and takes away the

oxygen. If I now put this potassium into

water, I find that besides the potash formed

(which you need not trouble about) there is a

quantity of carbon produced. I have here made

the experiment in a very rough way, but I as-

sure you that if I were to make it carefully, de-

voting a day to it instead of five minutes, we

should get all the proper amount of charcoal

left in the spoon, or in the place where the

potassium was burned, so that there could be

no doubt as to the result. Here, then, is the

carbon obtained from the carbonic acid, as a

common black substance ; so that you have the

CARBON IX WOOD AND COAL-GAS. 163

entire proof of the nature of carbonic acid as

consisting of carbon and oxygen. And nowI may tell you, that luhenever carbon burns

under common circumstances it produces car-

bonic acid.

Suppose I take this piece of wood, and put it

into a bottle with lime-water. I might shake

that lime-water up with wood and the atmos-

phere as long as I pleased, it would still remain

clear as you see it; but suppose I burn the

piece of wood in the air of that bottle. You,

of course, know I get water. Do I get carbonic

acid? [The experiment was performed.] There

it is, you see— that is to sa}^, the carbonate of

lime, which results from carbonic acid, and that

carbonic acid must be formed from the carbon

which comes from the wood, from the candle,

or any other thing. Indeed, you have your-

selves frequently tried a very pretty experi-

ment, by which you may see the carbon in

wood. If you take a piece of wood, and partly

burn it, and then blow it out, you have carbon

left. There are things that do not show carbon

in this way. A candle does not so show it, but

it contains carbon. Here also is a jar of coal-

164 GASEOUS PRODUCT OF COMBUSTION.

gas, which produces carbonic acid abundantly

;

you do not see the carbon, but we can soon

show it to you. I will light it, and as long as

there is any gas in this cylinder it will go on

burning. You see no carbon, but you see a

flame, and because that is bright it will lead

you to guess that there is carbon in the flame.

But I will show it to you by another process.

I have some of the same gas in another vessel,

mixed with a body that will burn the hydro-

gen of the gas, but will not burn the carbon.

I will light them with a burning taper, and you

perceive the hydrogen is consumed, but not the

carbon, which is left behind as a dense black

smoke. I hope that by these three or four ex-

periments you will learn to see when carbon is

present, and understand what are the products

of combustion when gas or other bodies are

thoroughly burned in the air.

Before we leave the subject of carbon, let us

make a few experiments and remarks upon its

wonderful condition as respects ordinary com-

bustion. I have shown you that the carbon, in

burning, burns only as a solid body, and yet

you perceive that, after it is burned, it ceases to

COMBUSTION" OF LEAD PYROPIIORUS. 165

be a solid. There are very few fuel^ that act

like this. It is, in fact, only that great source

of fuel, the carbonaceous series, the coals, char-

coals, and woods, that can do it. I do not

know that there is any other elementary sub-

stance besides carbon that burns with these

conditions; and if it had not been so, what

would happen to ns? Suppose all fuel had

been like iron, which, when it burns, burns into

a solid substance. We could not then have

such a combustion as you have in this fireplace.

Here also is another kind of fuel which burns

very well—as well as, if not better, than carbon

—so well, indeed, as to take fire of itself when

it is in the air, as you see. [Breaking a tube

full of lead pyrophorus.] This substance is

lead, and you see how wonderfully combustible

it is. It is very much divided, and is like a

heap of coals in the fireplace : the air can get

to its surface and inside, and so it burns. But

why does it not burn in that way now when it

is lying in a mass? [Emptying the contents

of the tube in a heap on to a plate of iron.]

Simply because the air can not get to it.

Though it can produce a great heat, the great

166 SOLID PRODUCTS OF COMBUSTION.

heat which we want in our furnaces and under

our boilers, still that which is produced can not

get away from the portion which remains un-

burned underneath, and that portion, therefore,

is prevented from coming in contact with the

atmosphere, and can not be consumed. IIow

different is that from carbon ! Carbon burns

just in the same way as this lead does, and so

gives an intense fire in the furnace, or wherever

you choose to burn it ; but then the body pro-

duced by its combustion passes away, and the

remaining carbon is left clear. I showed you

how carbon went on dissolving in the oxygen,

leaving no ash, whereas here [pointing to the

heap of pyrophorus] we have actually more ash

than fuel, for it is heavier by the amount of the

oxygen which has united with it. Thus you

see the difference between carbon and lead or

iron—if we chose iron, which gives so wonder-

ful a result in our applications of this fuel,

either as light or heat. If, when the carbon

burnt, the product went off" as a solid body, you

would have had the room filled with an opaque

substance, as in the case of the phosphorus;

but when carbon burns, every thing passes up

COMBUSTION AND RESPIRATION. 167

into the atmosphere. It is in a fixed, almost

unchangeable condition before the combustion

;

but afterward it is in the form of gas, which

it is very dif&cult (though w^e have succeeded)

to produce in a solid or liquid state.

Kow I must take you to a very interesting

part of our subject—to the relation between the

combustion of a candle and that living kind of

combustion which goes on within us. In every

one of us there is a living process of combustion

going on very similar to that of a candle, and

I must try to make that plain to you. For it

is not merely true in a poetical sense—the re-

lation of the life of man to a taper ; and if you

wall follow, I think I can make this clear. In

order to make the relation very plain, I have

devised a little apparatus which we can soon

build up before you. Here is a board, and a

groove cut in it, and I can close the groove at

the top part by a little cover ; I can then con-

tinue the groove as a channel by a glass tube

at each end, there being a free passage through

the whole. Suppose I take a taper or candle

(we can now be liberal in our use of the word

*' candle," since we understand what it means),

168 COMBUSTION AND RESPIRATION.

and place it in one of the tubes ; it will go on,

you see, burning very well. You observe that

Fig. 32.

the air which feeds the flame passes down the

tube at one end, then goes along the horizontal

tube, and ascends the tube at the other end in

which the taper is placed. If I stop the aper-

ture through which the air enters, I stop com-

bustion, as 3^ou perceive. I stop the supply of

air, and consequently the candle goes out. But

now what will you think of this fact? In a

former experiment I showed you the air going

from one burning candle to a second candle.

If I took the air proceeding from another can-

dle, and sent it down by a complicated ar-

rangement into this tube, I should put this

burning candle out. But what will you say

THE BREATH EXTINGUISHES COMBUSTION. 169

when I tell you that my brcatli will put out

that candle ? I do not mean by blowing at all,

but simply that the nature of my breath is such

that a candle can not burn in it. I will now

hold my mouth over the aperture, and without

blowing the flame in any way, let no air enter

the tube but what comes from my mouth. You

see the result. I did not blow the candle out.

I merely let the air which I expired pass into

the aperture, and the result was that the light

went out for w^ant of oxygen, and for no other

reason. Something or other—namely, my lungs

—had taken away the oxygen from the air, and

there was no more to supply the combustion of

the candle. It is, I think, very pretty to see

the time it takes before thd bad air which I

throw into this part of the apparatus has

reached the candle. The candle at first goes

on burning, but so soon as the air has had

time to reach it it goes out. And now I will

show you another experiment, because this is

an important part of our philosophy. Here

is a jar which contains fresh air, as you can see

by the circumstance of a candle or gas-light

burning it. I make it close for a little time,

170 PRODUCTS OF EESPIRATIOX.

and by means of a pipe I get my moutli over

it so that I can inhale the air. By putting it

Fig. 33.

over water, in the way that you see, I am able

to draw up this air (supposing the cork to be

quite tight), take it into my lungs, and throw

it back into the jar: we can then examine it,

and see the result. You observe, I first take

up the air, and then throw it back, as is evi-

dent from the ascent and descent of the water

;

and now, by putting a taper into the air, you

will see the state in which it is by the light be-

ing extinguished. Even one inspiration, you^

see, has completely spoiled this air, so that it

IMPORTANCE OF YEXTILATIOX. 171

is no use my trying to breathe it a second time.

Now you understand the ground of the impro-

priety of many of the arrangements among the

houses of the poorer classes, by which the air

is breathed over and over again for the want

of a supply, by means of proper ventilation,

sufficient to produce a good result. You see

how bad the air becomes by a single breathing,

so that you can easily understand how essen-

tial fresh air is to us.

To pursue this a little farther, let us see what

will happen with lime-water. Here is a globe

which contains a little lime-water, and it is so

arranged as regards the pipes as to give access

to the air within, so that we can ascertain the

effect of respired or unrespired air upon it. Of

172 ACTION OF BREATH ON LIME-WATER.

course I can either draw in air (tbrougli A), and

so make the air that feeds my lungs go through

the lime-water, or I can force the air out of mylungs through the tube (b), which goes to the

bottom, and so show its effect upon the lime-

water. You will observe that however long I

draw the external air into the lime-water, and

then through it to my lungs, I shall produce no

effect upon the water— it will not make the

lime-water turbid; but if I throw the air //-cm

my lungs through the lime-water several times

in succession, you see how white and milky the

water is getting, showing the effect which, ex-

pired air has had upon it ; and now you begin

to know that the atmosphere which we have

spoiled by respiration is spoiled by carbonic

acid, for you see it here in contact with the

lime-water.

I have here two bottles, one containing lime-

water and the other common water, and tubes

which pass into the bottles and connect them.

The apparatus is very rough, but it is useful

notwithstanding. If I take these two bottles,

inhaling here and exhaling there, the arrange-

ment of the tubes will prevent the air going

ACTION OF BREATH ON LIME-WATER. 173

backward. The air coming in will go to my

mouth and lungs, and in going out will pass

Fig. 35.

through the lime-water, so that I can go on

breathing, and making an experiment very re-

fined in its nature and very good in its results.

You will observe that the good air has done

nothing to the lime-water; in the other case,

nothing has come to the lime-water but my

respiration, and you see the difference in the

two cases.

Let us now go a little farther. What is all

this process going on within us which we can

not do without, either day or night, which is

174 WHAT IS RESPIRATION?

SO provided for by the Author of all things

that He has arranged that it shall be indepen-

dent of all will? If we restrain our respira-

tion, as we can to a certain extent, we should

destroy ourselves. When we are asleep, the

organs of respiration and the parts that are as-

sociated with them still go on with their ac-

tion, so necessary is this process of respiration

to us, this contact of the air with the lungs. I

must tell you, in the briefest possible manner,

what this process is. "We consume food ; the

food goes through that strange set of vessels

and organs within us, and is brought into va-

rious parts of the system, into the digestive

parts especially; and alternately the portion

which is so changed is carried through our

lungs by one set of vessels, while the air that

we inhale and exhale is drawn into and thrown

out of the lungs by another set of vessels, so

that the air and the food come close together,

separated only by an exceedingly thin surface

:

the air can thus act upon the blood by this pro-

cess, producing precisely the same results in

kind as we liavc seen in the case of the candle.

The candle combines with parts of the air, form-

CAKBONIC ACID FORMED BY RESPIRATION. 175

ing carbonic acid, and evolves heat ; so in the

lungs there is tliis curious, wonderful change

taking place. The air entering, combines with

the carbon (not carbon in a free state, but, as

in this case, placed ready for action at the mo-

ment), and makes carbonic acid, and is so

thrown out into the atmosphere, and thus this

singular result takes place ; we may thus look

upon the food as fuel. Let me take that piece

of sugar, which will serve my purpose. It is

a compound of carbon, hydrogen, and oxygen,

similar to a candle, as containing the same el-

ements, though not in the same proportion,

the proportions being as shown in this table

:

Sugar.

Carbon 72

Hydrogen ll")^^

Oxygen 88 j""^

This is, indeed, a very curious thing, which

you can well remember, for the oxygen and

hydrogen are in exactly the proportions which

form water, so that sugar may be said to be

compounded of 72 parts of carbon and 99 parts

of water ; and it is the carbon in the sugar that

combines with the oxygen carried in by the air

in the process of respiration, so making us like

176 CARBON PRESENT IN FOOD.

candles;producing these actions, warmth, and

far more wonderful results besides, for the sus-

tenance of the system, by a most beautiful and

simple process. To make this still more strik-

ing, I will take a little sugar; or, to hasten

the experiment, I will use some sirup, which

contains about three fourths of sugar and a

little water. If I put a little oil of vitriol on

it, it takes away the water, and leaves the car-

bon in a black mass. [The lecturer mixed the

two together.] You see how the carbon is

coming out, and before long we shall have a

solid mass of charcoal, all of which has come

out of sugar. Sugar, as you know, is food, and

here we have absolutely a solid lump of carbon

where you would not have expected it. And

if I make arrangements so as to oxidize the car-

bon of sugar, we shall have a much more strik-

ing result. Here is sugar, and I have here an

oxidizer—a quicker one than the atmosphere

;

and so we shall oxidize this fuel by a process

different from respiration in its form, though

not different in its kind. It is the combustion

of the carbon by the contact of oxygen which

the body has Bupplied to it. If I set this into

CARBON BURNED DURING RESPIRATION. 177

action at once, you will see combustion pro-

duced. Just what occurs in my lungs—taking

in oxygen from another source, namely, the

atmosphere, takes place here by a more rapid

process.

You will be astonished when I tell you what

this curious play of carbon amounts to. Acandle will burn some four, five, six, or seven

hours. What, then, must be the daily amount

of carbon going up into the air in the way of

carbonic acid ! What a quantity of carbon

must go from each of us in respiration ! What

a wonderful change of carbon must take place

under these circumstances of combustion or

respiration ! A man in twenty-four hours con-

verts as much as seven ounces of carbon into

carbonic acid ; a milch cow will convert seven-

ty ounces, and a horse seventy-nine ounces,

solely by the act of respiration. That is, the

horse in twenty-four hours burns seventy-nine

ounces of charcoal, or carbon, in his organs of

respiration to supply his natural warmth in that

time. All the warm-blooded animals get their

warmth in this way, by the conversion of car-

bon, not in a free state, but in a state of combi-

M

178 VALUE OF CARBONIC ACID TO PLANTS.

nation. And what an extraordinary notion

tliis gives us of the alterations going on in our

atmosphere. As much as 5,000,000 pounds, or

548 tons, of carbonic acid is formed by respira-

tion in London alone in twenty-four hours.

And where does all this go? Up into the air.

If the carbon had been like the lead which I

showed you, or the iron which, in burning, pro-

duces a solid substance, what w^ould happen?

Combustion could not go on. As charcoal

burns it becomes a vapor and passes off into

the atmosphere, which is the great vehicle, the

great carrier for conveying it away to other

places. Then what becomes of it ? Wonder-

ful is it to find that the change produced by

respiration, w^hich seems so injurious to us (for

we can not breathe air twice over), is the very

life and support of plants and vegetables that

grow upon the surface of the earth. It is the

same also under the surface, in the great bodies

of water ; for fishes and other animals respire

upon the same principle, though not exactly

by contact with the open air.

Such fish as I have here [pointing to a

globe of gold-fish] respire by the oxygen which

GROWTH OF TREES AND PLANTS. 179

is dissolved from the air by the water, and

form carbonic acid, and they all move about to

produce the one great work of making the an-

imal and vegetable kingdoms subservient to

each other. And all the plants growing upon

the surface of the earth, like that which I have

brouo-ht here to serve as an illustration, absorb

carbon ; these leaves are taking up their carbon

from the atmosphere to which we have given it

in the form of carbonic acid, and they are

growing and prospering. Give them a pure air

like ours, and they could not live in it; give

them carbon with other matters, and they live

and rejoice. This piece of wood gets all its

carbon, as the trees and plants get theirs, from

the atmosphere, which, as we have seen, carries

away what is bad for us and at the same time

good for them—what is disease to the one be-

ing health to the other. So are we made de-

pendent not merely upon our fellow-creatures,

but upon our fellow-existers, all Nature being

tied together by the laws that make one part

conduce to the good of another.

There is another little point which I must

mention before we draw to a close— a point

180 LEAD BURNS AT ONCE.

wbicli concerns the whole of these operations,

and most curious and beautiful it is to see it

clustering upon and associated with the bodies

that concern us— oxygen, hydrogen, and car-

bon, in different states of their existence. I

showed you just now some powdered lead,

which I set burning ;(^^) and joii saw that the

moment the fuel was brought to the air it acted,

even before it got out of the bottle— the mo-

ment the air crept in it acted. IS^ow there is a

case of chemical affinity by which all our ope-

rations proceed. When we breathe, the same

operation is going on within us. When we

burn a candle, the attraction of the different

parts one to the other is going on. Here it is

going on in this case of the lead, and it is a

beautiful instance of chemical affinity. If the

products of combustion rose off from the sur-

face, the lead would take fire, and go on burn-

ing to the end ; but you remember that we have

this difference between charcoal and lead—that,

while the lead can start into action at once if

there be access of air to it, the carbon will re-

main days, weeks, months, or years. The man-

uscripts of Herculaneum were written with car-

CARBON WAITS IN ITS ACTION. 181

bonaceous ink, and there they have been for

1800 years or more, not having been at all

changed by the atmosphere, though coming in

contact with it under various circumstances.

Now, what is the circumstance which makes

the lead and carbon differ in this respect ? It

is a striking thing to see that the matter which

is appointed to serve the purpose of fuel icaits

in its action ; it does not start off burning, like

the lead and many other things that I could

show you, but which I have not encumbered

the table with ; but it waits for action. This

waiting is a curious and wonderful thing. Can-

dles—those Japanese candles, for instance—do

not start into action at once like the lead or iron

(for iron finely divided does the same thing as

lead), but there they wait for years, perhaps for

ages, without undergoing any alteration. I

have here a supply of coal-gas. The jet is giv-

ing forth the gas, but you see it does not take

fire—it comes out into the air, but it waits till

it is hot enough before it burns. If I make it

hot enough, it takes fire. If I blow it out, the

gas that is issuing forth waits till the light is ap-

plied to it again. It is curious to see how dif-

182 RESPIRATION AND COMBUSTION.

ferent substances wait—how some will wait till

the temperature is raised a little, and others till

it is raised a good deal. I have here a little

gunpowder and some gun-cotton ; even these

things differ in the conditions under which they

will burn. The gunpowder is composed of car-

bon and other substances, making it highly com-

bustible ;and the gun-cotton is another com-

bustible preparation. They are both waiting,

but they will start into activity at different de-

grees of heat, or under different conditions.

By applying a heated wire to them, we shall

see which will start first [touching the gun-

cotton with the hot iron]. You see the gun-

cotton has gone off, but not even the hottest

part of the wire is now hot enough to fire the

gunpowder. How beautifully that shows you

the difference in the degree in which bodies act

in this way ! In the one case the substance will

wait any time until the associated bodies are

made active by heat; but in the other, as in

the process of respiration, it waits no time. In

the lungs, as soon as the air enters, it unites

with the carbon ; even in the lowest tempera-

ture which the body can bear short of being

CONCLUSION. 183

frozen, the action begins at once, producing the

carbonic acid of respiration;and so all things

go on fitly and properly. Thus you see the

analogy between respiration and combustion is

rendered still more beautiful and striking. In-

deed, all I can say to you at the end of these

lectures (for we must come to an end at one

time or other) is to express a wish that you may,

in your generation, be fit to compare to a can-

dle; that you may, like it, shine as lights to

those about you ; that, in all your actions, you

may justify the beauty of the taper by making

your deeds honorable and effectual in the dis-

charge of your duty to your fellow-men.

LECTURE ON PLATINUM.

IDelivered before the Royal Institution on Friday,

February 22, 1861.]

Whether I was to have tlie honor of ap-

pearing before you this evening or not seemed

to be doubtful upon one or two points. One

of these I will mention immediately;the other

may or may not appear during the course of

the hour that follows. The first point is this.

When I was tempted to propose this subject

for your attention this evening, it was founded

upon a promise, and a full intent of performing

that promise, on the part of my friend Deville,

of Paris, to come here to show before jow a

phenomenon in metallurgic chemistry not com-

mon. In that I have been disappointed. His

intention was to have fused here some thirty or

forty pounds of platinum, and so to have made

manifest, through my mouth and my statement,

the principles of a new process in metallurgy

186 SOURCES OF PLATINUM.

ill relation to this beautiful, magnificent, and

valuable metal ; but circumstances over which

neither he nor I, nor others concerned, have

sufficient control, have prevented the fulfillment

of that intention, and the period at which I

learned the fact was so recent that I could hard-

ly leave my place here to be filled by another,

or permit you, who in your kindness have come

here to hear what might be said, to remain un-

received in the best manner possible to me un-

der the circumstances. I therefore propose to

state as well as I can what the principles are

on which M. Deville proceeds, by means of

drawings, and some subordinate or inferior ex-

periments.

The metal platinum, of which you see some

very fine specimens on the table, has been

known to us about a hundred years. It has

been wrought in a beautiful way in this coun-

try, in France, and elsewhere, and supplied to

the consumer in ingots of this kind, or in plates,

such as we have here, or in masses, that by

their very fall upon the table indicate the great

weight of the substance, which is, indeed, near-

ly at the head of all substances in that respect.

METALS ASSOCIATED WITH PLATINUM. 187

This substance has been given to us hitherto

mainly through the philosophy of Dr. Wollas-

ton, whom many of us know, and it is obtain-

ed in great purity and beauty. It is a very re-

markable metal in many points besides its

known special uses. It usually comes to us in

grains. Here is a very fine specimen of native

platinum in grains. Here is also a nugget or

ingot, and here are some small pieces gathered

out of certain alluvial soils in Brazil, Mexico,

California, and the Uralian districts of Eussia.

It is strange that this metal is almost always

found associated with some four or five other

metals, most curious in their qualities and char-

acteristics. They are called platiniferous met-

als;and they have not only the relation of be-

ing always found associated in this manner, but

they have other relations of a curious nature,

which I shall point out to joi\ by a reference

to one of the tables behind me. This substance

is always native, it is always in the metallic

state, and the metals with which it is found

connected, and which are rarely found else-

where, are palladium, rhodium, iridium, osmi-

um, and ruthenium. We have the names in

188 MEMBERS OF THE PLATINUM GROUP.

one of the tables arranged in two columns, rep-

resenting, as you see, two groups;platinum,

iridium, and osmium constituting one group,

and ruthenium, rhodium, and palladium the

other. Three of these have the chemical equiv-

alent of 98|, and the others a chemical equiva-

lent of about half that number. Then the met-

als of one group have an extreme specific grav-

ity, platinum being, in fact, the lightest of the

three, or as light as the lightest. Osmium has

a specific gravity of 214, and is the heaviest

body in nature;platinum is 21-15, and iridium

the same ; the specific gravity of the other

three being only about half that, namely, 11*3,

121, and 11-8. Then there is this curious re-

lation, that palladium and iridium are very

much alike, so that you would scarcely know

one from the other, though one has only half

the weight of the other, and only half the equiv-

alent power. So with iridium and rhodium,

and osmium and ruthenium, which are so close-

ly allied that they make pairs, being separated

each from its own group. Then these metals

are the most infusible that we possess. Osmi-

um is the most difficult to fuse; indeed, I be-

EXTRACTION BY THE WET PROCESS. 189

lieve it never has been fused, while every oth-

er metal has ;ruthenium comes next, iridium

next, rhodium next, platinum next (so that it

ranks here as a pretty fusible metal, and yet

we have been long accustomed to speak of the

infusibility of platinum), and next comes palla-

dium, which is the most fusible metal of the

whole. It is a curious thing to see this fine as-

sociation of physical properties coming out in

metals which are grouped together somehow or

other in nature, but, no doubt, by causes which

are related to analogous properties in their sit-

uation on the surface of the earth, for it is in

alluvial soils that these things are found.

Now, with regard to this substance, let me

tell you briefly how we get it. The process

used to be this. The ore which I showed you

just now was taken and digested in nitro-mu-

riatic acid of a certain strength, and partly con-

verted into a solution, with the leaving behind

of certain bodies that I have upon the table.

The platinum being dissolved with care in

acids, to the solution the muriate of ammonia

was added, as I am about to add it here. Ayellow precipitate was then thrown down, as

190 SPONGY PLATINUM.

you perceive is the case now ; and this, care-

fully washed and cleansed, gave us that body

[pointing to a specimen of the chloride of pla-

tinum and ammonium], the other elements, or

nearly all, being ejected. This substance being

heated, gave us what we call platinum sponge,

or platinum in the metallic state, so finely di-

vided as to form a kind of heavy mass or

sponge, which, at the time that Dr.Wollaston

first sent it forth, was not fusible for the mar-

ket or in the manufacturers' workshops, inas-

much as the temperature required was so high,

and there were no furnaces that could bring

the mass into a globule, and cause the parts to

adhere together. Most of our metals that we

obtain from nature, and work in our shops, are

brought at last into a mass by fusion. I am

not aware that there is in the arts or sciences

any other than iron which is not so. Soft iron

we do not bring together by fusion, but by a

process which is analogous to the one that was

followed in the case of platinum, namely, weld-

ing ; for these divided grains of spongy plati-

num having been well washed and sunk in wa-

ter for the purpose of excluding air, and press-

WELDING PROPERTY OF PLATINUM. 191

ed together, and heated, and hammered, and

pressed again, until they come into a pretty

close, dense, compact mass, did so cohere, that

when the mass was put into the furnace of

charcoal, and raised to a high temperature, the

particles, at first infinitely divided— for they

were chemically divided—adhered the one to

the other, each to all the rest, until they made

that kind of substance which you see here,

which will bear rolling and expansion of every

kind. No other process than that has hitherto

been adopted for the purpose of obtaining this

substance from the particles by solution, pre-

cipitation, ignition, and welding. It certainly

is a very fine thing to see that we may so fully

depend upon the properties of the various sub-

stances we have to deal with, that we can, by

carrying out our processes, obtain a material

like this, allowing of division and extension

under a rolling mill— a material of the finest

possible kind, the parts being held together,

not with interstices, not with porosity, but so

continuous that no fluids can pass between

them ; and, as Dr. Wollaston beautifully show-

ed, a globule of platinum fused by the voltaic

192 WELDING PROPERTY OF PLATINUM.

battery and the oxj^bydrogcn blowpipe, when

drawn into a wire, was not sounder or stronger

than this wire made by the curious coalescence

of the particles by the sticking power that they

had at high temperatures. This is the process

adopted by Messrs. Johnson and Matthey, to

whose great kindness I am indebted for these

ingots and for the valuable assistance I have

received in the illustrations.

The treatment, however, that I have to bring

before you is of another kind, and it is in the

hope that we shall be able before long to have

such a thing as the manufacture of platinum of

this kind that I am encouraged to come before

you, and tell you how far Deville has gone in

the matter, and to give you illustrations of the

principles on which he proceeds. I think it is

but fair that you should see an experiment

showing you the way in which we get the ad-

hesion of platinum. Probably you all know of

the welding of iron;you go into the smith's

shop, and you see him put the handle ofa poker

on to the stem, and by a little management and

the application of heat he makes them one.

You have no doubt seen him put the iron into

WELDING PROPERTY OF PLATINUM. 193

the fire and sprinkle a little sand upon it. He

does not know the philosophy he calls into

play when he sprinkles a little sand over the

oxide of iron, but he has a fine philosophy

there, or practices it, when he gets his welding.

I can show you here this beautiful circumstance

of the sticking together of the particles up to

the fullest possible intensity of their combina-

tion. If you were to go into the workshops of

Mr. Matthey, and see them hammering and

welding away, you would see the value of the

experiment I am about to show you. I have

here some platinum wire. This is a metal

which resists the action of acids, resists oxida-

tion by heat, and change of any sort, and which,

therefore, I may heat in the atmosphere with-

out any flux. I bend the wire so as to make

the ends cross : these I make hot by means of

the blowpipe, and then, by giving them a tap

with a hammer, I shall make them into one

piece. Now that the pieces are united, I shall

have great difiiculty in pulling them apart,

though they are joined only at the point where

the two cylindrical surfaces came together.

And now I have succeeded in pulling the wire

194 COMPOSITION OF PLATINUM ORE.

apart, the division is not at the point of welding,

but where the force of the pincers has cut it, so

that the junction we have effected is a complete

one. This, then, is the principle of the manu-

facture and production of platinum in the old

way.

The treatment which Deville proposes to

carry out, and which he has carried out to a

rather large extent in reference to the Eussian

supply of platinum, is one altogether by heat,

having little or no reference to the use of acids.

That you may know what the problem is, look

at this table, which gives you the composition

of such a piece of platinum ore as I showed you

just now. Wherever it comes from, the com-

position is as complicated, though the propor-

tions vary.

Platinnm 76.4

Iridium 4.3

Rhodium 0-3

Palladium 1.4

Gold 0.4

Copper 4.1

Iron 11-7

Osmide of iridium 0.5

Sand 1-4

100.5

This refers to the Uralian ore. In that state of

PLATINUM COIN. 195

combination as shown in the table, the iridium

and osmium are found combined in crystals

sometimes to the amount of 0*5 per cent., and

sometimes 3 or 4 per cent. Now this Deville

proposes to deal with in the dry way, in the

place of dealing with it by any acid.

I have here another kind of platinum ; and I

show it to you for this reason. The Eussian

government, having large stores of platinum in

their dominions, have obtained it in a metallic

state and worked it into coin. The coin I have

in my hand is a twelve silver ruble piece. The

ruble is worth three shillings, and this coin is

therefore of the value of thirty-six shillings.

The smaller coin is worth half that sum ; and

the other, half of that. The metal, however, is

unfit for coinage. When you have the two

metals, gold and silver, used for coinage, you

have a little confusion in the value of the two

in the market ; but when you have three pre-

cious metals (for you may call platinum a pre-

cious metal) worked into coin, they will be sure

to run counter to one another. Indeed, the

case did happen that the price of platinum coin

fixed by the government was such that it was

196 VOLATILITY OF METALS.

worth while to purchase platinum in other

countries and make coin of it, and then take it

into that country and circulate it. The result

was, that the Russian government stopped the

issue. The composition of this coin is—plati-

num, 97*0 ; iridium, 1-2 ; rhodium, 0*5;palla-

dium, 0-25 ; a little copper, and a little iron.

It is, in fact, bad platinum ; it scales, and it

has an unfitness for commercial use and in the

laboratory, which the other well-purified plati-

num has not. It wants working over again.

Now Deville's process depends upon three

points—upon intense heat, blowpipe action, and

the volatility of certain metals. We know that

there are plenty of metals that are volatile, but

this, I think, is the first time that it has been

proposed to use the volatility of certain metals,

such as gold and palladium, for the purpose of

driving them off and leaving something else

behind. He counts largely upon the volatility

of metals which we have not been in the habit

of considering volatile, but which we have rath-

er looked upon as fixed ; and I must endeavor

to illustrate these three points by a few exper-

iments. Perhaps I can best show you what is

VOLTAIC IGNITION OF WIRE. 197

required in the process of heating platinum by

using that source of heat which we have here,

and which seems to be almost illimitable, name-

ly, the voltaic battery ; for it is only in conse-

quence of the heat that the voltaic battery af-

fects the platinum. By applying the two ex-

tremities of the battery to this piece of plati-

num wire, you will see what result we shall

obtain. You perceive that we can take about

this heating agent wherever we like, and deal

with it as we please, limiting it in any way. I

am obliged to deal carefully with it ; but even

that circumstance will have an interest for you

in watching the experiment. Contact is now

made. The electric current, when compressed

into thin conducting wires offering resistance,

evolves heat to a large extent, and this is the

power by which we work. You see the intense

glow immediately imparted to the wire ; and

if I applied the heat continuously, the effect

of the current would be to melt the wire. As

soon as the contact is broken, the wire resumes

its former appearance ; and now that we make

contact again, you perceive the glow as before.

[The experiment was repeated several times in

198 VOLTAIC ignitio:n' of wire.

rapid succession.] You can see a line of light,

though you can scarcely perceive the wire;

and now that it has melted with the great heat,

if you examine it you will perceive that it is

indeed a set of irregularities from end to end

—a set of little spheres, which are strung upon

an axis of platinum running through it. It is

that wire which Mr. Grove described as being

produced at the moment when fusion of the

whole mass is commencing. In the same man-

ner, if I take a tolerably thick piece of plati-

num, and subject it to the heat that can be pro-

duced by this battery, you will see the brillian-

cy of the effect produced. I shall put on a

pair of spectacles for the experiment, as there

is an injurious effect of the voltaic spark upon

the eyes if the action is continued, and it is

neither policy nor bravery to subject any or-

gan to unnecessary danger, and I want, at all

events, to keep the full use of my eyes to the

end of the lecture.

You now see the action of the heat upon the

piece of platinum—heat so great as to break in

pieces the plate on which the drops of metal

fall. You perceive, then, that we have sufl&-

VOLTAIC FUSION OF PLATINUM. 199

ciently powerful sources of heat in nature to

deal with platinum. I have here an apparatus

by which the same thing can be shown. Here

is a piece of platinum, which is put into a cru-

cible of carbon made at the end of one pole

of the battery, and you will see the brilliant

light that will be produced. There is our fur-

nace, and the platinum is rapidly getting heat-

ed; and now you perceive that it is melted,

and throwing off little particles. What a

magnificent philosophical instrument this is!

When you look at the result, which is lying

upon the charcoal, you will see a beautifully

fused piece of platinum. It is now a fiery

globule, with a surface so bright, and smooth,

and reflecting that I can not tell whether it is

transparent, or opaque, or what. This, then,

will give you an idea of what has to be done

by any process that pretends to deal with thir-

ty, or forty, or fifty pounds of platinum at once.

Let me now tell you briefly what Deville

proposes to do. First of all, he takes this ore

with its impurities and mixes it (as he finds it

essential and best) with its own weight of sul-

phuret of lead—^lead combined with sulphur.

200 VOLTAIC FUSION OF PLATINUM.

Both the lead and the sulphur are wanted; for

the iron that is there present, as jom see bj the

table, is one of the most annoying substances in

the treatment that you can imagine, because it

is not volatile ; and while the iron remains ad-

hering to the platinum, the platinum will not

flow readily. It can not be sent away by a high

temperature— sent into the atmosphere so as

to leave the platinum behind. Well, then, a

hundred parts of ore and a hundred parts of

sulphuret of lead, with about fifty parts of me-

tallic lead, being all mingled together in a cru-

cible, the sulphur of the sulphuret takes the

iron, the copper, and some of the other metals

and impurities, and combines with them to

form a slag; and as it goes on boiling and

oxidizing, it carries off the iron, and so a great

cleansing takes place.

Now you ought to know that these metals,

such as platinum, iridium, and palladium, have

a strong affinity for such metals as lead and tin,

and upon this a great deal depends. Yery much

depends upon the platinum throwing out its

impurities of iron and so forth by being taken

up with the lead present in it. That you may

FUSION OF PLATINUM WITH LEAD. 201

have a notion of the great power that platinum

has of combining with other metals, I will refer

you to a little of the chemist's experience—his

bad experience. He knows very well that if

he takes a piece of platinum-foil and heats a

piece of lead upon it, or if he tako3 a piece of

platinum-foil, such as we have here, and heats

things upon it that have lead in them, his plati-

num is destroyed. I have here a piece of plati-

num, and if I apply the heat of the spirit-lamp

to it, in consequence of the presence of this little

piece of lead which I will place on it, I shall

make a hole in the metal. The heat of the

lamp itself would do no harm to the platinum,

nor would other chemical means ; but because

there is a little lead present, and there is an

affinity between the two substances, the bodies

fuse together at once. You see the hole I

have made. It is large enough to put your

finger in, though the platinum itself was, as

you saw, almost infusible, except by the voltaic

battery. For the purpose of showing this fact

in a more striking manner, I have taken pieces

of platinum-foil, tin-foil, and lead-foil, and roll-

ed them together; and if I apply the blow-

202 FUSION OF PLATINUM WITH LEAD.

pipe to them, you will have, in fact, a repetition

on a larger scale of the experiment you saw

just now when the lead and platinum came

together, and one spoiled the other. Whenthe metals are laid one upon the other, and

folded together, and heat applied, you will not

only sec that the platinum runs to waste, but

that, at the time when the platinum and lead

are combined, there is ignition produced, there

is a power of sustaining combustion. I have

taken a large piece, that you may see the phe-

nomenon on a large scale. You saw the igni-

tion and the explosion which followed, of which

we have here the results—the consequence of

the chemical affinity between the platinum and

the metals combined with it, which is the thing

upon which Deville founds his first result.

When he has melted these substances, and

stirred them up well, and so obtained a com-

plete mixture, ht throws in air upon the sur-

face to burn off all the sulphur from the remain-

ing sulphuret of lead ; and at last he gets an

ingot of lead with platinum— much lead com-

paratively, and little platinum. He gets that

in the crucible with a lot of scoriae and other

CUPELLATION OF PLATINUM. 203

tilings, which he treats afterward. It is that

platiniferous lead which we have to deal with

in our future process. Now let me tell you

what he does with it. His first object is to get

rid of the lead. He has thrown out all the iron,

and a number of other things, and he has got

this kind of compound indicated in the table.

He may get it as high as 78 per cent, of plati-

num and 22 of lead ; or 5, or 10, or 15 of plati-

num and 95, or 90, or 85 of lead (which he

calls weak platinum), and he then places it in

the kind of vessel that you see before you.

Fig. 36.

Suppose we had the mixture here ; we should

have to make it hot, and then throw in air upon

the surface. The combustible metal—that is,

the lead— and the part that will oxidize are

204: CUPELLATIOX OF PLATINUM.

thoroughly oxidized ; the litharge would flow-

out in a fused state into a vessel placed to re-

ceive it, and the platinum remains behind.

Here is the process which Deville adopts for

the purpose of casting off the lead after he has

got out the platinum from the ore. (Having

made use of your friend, you get rid of him as

quickly as you can.) He gets his heat by ap-

plying the combination of oxygen and hydro-

gen, or of carbureted fuel, for the purpose of

producing a fire. I have here a source of coal-

gas ; there I have a source of hydrogen ; and

here I have a source of oxygen. I have here

also one of the blowpipes used by Deville in

OXYIIYDROGEN BLOWPIPE. 205

his process for working platinum in the way I

have spoken of. There are two pipes, and one

of them goes to the source of coal-gas, and the

other to the supply of oxygen. By uniting

these we obtain a flame of such a heat as to

melt platinum. You will perhaps hardly im-

agine what the heat is unless you have some

proof of it ; but you will soon see that I have

actually the power of melting platinum. Here

is a piece of platinum-foil running like wax

under the flame which I am bringing to bear

against it. The question, however, is whether

we shall get heat enough to melt, not this small

quantity, but large masses— many pounds of

the metal. Having obtained heat like this, the

next consideration is, what vessel is he to em-

ploy which could retain the platinum when so

heated, or bear the effects of the flame ? Such

vessels are happily well supplied at Paris, and

are formed of a substance which surrounds

Paris : it is a kind of chalk (called, I believe,

by geologists, calcaire grossiere), and it has the

property of enduring an extreme degree of

heat. I am now going to get the highest heat

that we can obtain. First, I show you the

206 THE LIME-LIGHT.

combustion of hydrogen by itself. I have not

a large supply, because the coal-gas is sufficient

for most of our purposes. If I put a piece of

lime obtained from this chalk into the gas, you

see we get a pretty hot flame, which would burn

one's fingers a good deal. But now let mesubject a piece of it to the joint action of oxy-

gen and hydrogen. I do this for the purpose

of showing you the value of lime as a material

for the furnaces and chambers that are to con-

tain the substances to be operated on, and that

are consequently to sustain the action of this

extreme heat. Here we have the hydrogen

and the oxygen, which will give the most in-

tense heat that can be obtained by chemical

action ; and if I put a piece of lime into the

flame, we get what is called the lime -light.

Now, with all the beauty and intensity of ac-

tion which you perceive, there is no sensible

deterioration of the lime except by the mechan-

ical force of the current of gases rushing from

the jet against the lime, sweeping away such

particles as are not strongly aggregated. "Va-

por of lime" some call it, and it may be so ; but

there is no other chans^e of the lime than that

ADVANTAGE OF THE BLOWPIPE. 207

under the action of heat of this highly-exalted

chemical condition, though almost any other

substance would melt at once.

Then as to the way in which the heat is ap-

pHed to the substance. It is all very well for

me to take a piece of antimony, and fuse it in

the flame of a blowpipe. But if I tried this

piece in the ordinary lamp-flame I should do

nothing ; if I tried a smaller piece I should do

little or nothing ; and if I tried a still smaller

piece I should do little or nothing;yet I have

a condition which will represent what Deville

carries to the highest possible extent, and which

we all carry to the highest extent in the use

of the blowpipe. Suppose I take this piece of

antimony : I shall not be able to melt it in that

flame of the candle by merely holding it there

;

yet, by taking pains, we can even melt a piece

of platinum there. This is a preparation which

I made for the purpose of proving the fusibil-

ity of platinum in a common candle. There

is a piece of wire drawn by that ingenious proc-

ess of Dr. Wollaston's, not more than the three

thousandth part of an inch in diameter. He

put the wire into the middle of a cylinder of

208 ADVANTAGE OF THE BLOWPIPE.

silver, and drew both together until the whole

compound was exceedingly thin, and then he

dissolved away the silver by nitric acid. There

was left in the centre a substance which I can

scarcely see with an eye-glass, but which I

know is there, and which I can make visible,

as you see, by putting it into the candle where

the heat makes it glow like a spark. I have

again and again tried this experiment up stairs

in my own room, and have easily fused this

platinum wire by a common candle. You see

we have, therefore, heat enough in the candle,

as in the voltaic battery or in the highly-ex-

alted combustion of the blowpipe, but we do

not supply a continuous source of heat. In

the very act of this becoming ignited the heat

radiates so fast that you can not accumulate

enough to cause the fusion of the wire except

under the most careful arrangement. Thus I

can not melt that piece of antimony by simply

putting it into the candle ; but if I put it upon

charcoal and drive the fiery current against it,

there will be heat enough to melt it. The

beauty of the blowpipe is that it sends hot air

(making hot air by the combustion of the flame)

FUSION OF ANTIMONY. 209

against the thing to be heated. I have only to

hold the antimony in the course of that cur-

rent, and particle by particle of the current

impinges upon the antimony, and so we get it

melted. You now see it red-hot, and I have

no doubt it will continue to burn if I with-

draw it from the flame and continue to force

the air on it. Now you see it burning with-

out any heat but that of its own combustion,

which I am keeping up by sending the air

against it. It would go out in a moment if I

took away the current of air from it ; but there

it is burning, and the more air I give it by this

or any other action, the better it is. So, then,

we have here not merely a mighty source of

heat, but a means of driving the heat forcibly

against substances.

Let me show you another experiment with

a piece of iron : it will serve two purposes—showing you what the blowpipe does as a

source of heat, and what it does by sending

that heat where it is wanted. I have taken

iron in contrast with silver or other metals,

that you may see the difference of action, and

so be more interested in the experiment. Here

O

210 FUSION OF IRON.

is our fuel, the coal-gas ; and here our oxygen.

Having thus my power of heat, I apply it to

the iron, which, as you see, soon gets red-hot.

It is now flowing about like a globule of melt-

ed mercury. But observe, I can not raise any

vapor : it is now covered with a coat of melted

oxide, and unless I have a great power in myblowpipe, it is hardly possible to break through

it. Now, then, you see these beautiful sparks

:

you have not only a beautiful kind of com-

bustion, but you see the iron is being driven

off; not producing smoke, but burning in a

fixed condition. How different this is from the

action of some other metals—that piece of an-

timony, for instance, which we saw just now

throwing off abundance of fumes ! We can, of

course, burn away this iron by giving plenty

of air to it ; but with the bodies which Deville

wants to expose to this intense heat he has not

that means; the gas itself must have power

enough to drive off the slag which forms on the

surface of the metal, and power to impinge

upon the platinum so as to get the full contact

that he wants for the fusion to take place. Wesee here, then, the means to which he resorts

:

211

oxygen, and either coal-gas, or water-gas,(^^) or

pure lijdrogen, for producing heat, and the

blowpipe for the purpose of impelling the heat-

ed current upon the metals.

I have two or three rough drawings here,

representing the kind of furnaces which he em-

ploys. They are larger, however, than the ac-

tual furnaces he uses. Even the furnace in

which he carries on that most serious operation

of fusing fifty pounds of platinum at once is not

much more than half the size of the drawing.

It is made of a piece of lime below and a piece

of lime above. You see how beautifully lime

sustains heat without altering in shape; and

you may have thought how beautifully it pre-

vents the dissipation of the heat by its very

bad conducting powers. While the front part

of the lime which you saw here was so highly

ignited, I could at any moment touch the back

of it without feeling any annoyance from the

heat. So, by having a chamber of lime of this

sort, he is able to get a vessel to contain these

metals with scarcely any loss of heat. Heputs the blowpipes through these apertures,

and sends down these gases upon the metals,

212 deville's platinum furnace.

which are gradually melted. He then puts in

more metal through a hole at the top. The

Fig. 3S.

results of the combustion issue out of the aper-

ture which you see represented. If there be

strips of platinum, he pushes them through the

mouth out of which the heated current is com-

ing, and there they get red-hot and white-hot

before they get into the bath of platinum. So

he is able to fuse a large body of platinum in

this manner. When the platinum is melted,

he takes oflP the top and pours out from the

bottom piece, like a crucible, and makes his

FUSION OF PLATINUM IN QUANTITY. 213

cast. This is the furnace by which, he fuses his

forty pounds or fifty pounds of platinum at

once. The metal is raised to a heat that no eye

can bear. There is no light and shadow, no

chiar-oscuro there ; all is the same intensity of

glow: you look in, and you can not see where

the metal or the lime is ; it is all as one. Wehave, therefore, a platform with a handle, which

turns upon an axis, that coincides with the

gutter that is formed for the pouring of the

metal ; and when all is known to be ready, by

means of dark glasses, the workmen take off

the top piece and lift up the handle, and the

mould being then placed in a proper position,

he knows that the issue of the metal will be

exactly in the line of the axis. Ko injury has

ever happened from the use of this plan. Youknow with what care it is necessary to carry

such a vessel of mercury as we have here, for

fear of turning it over on one side or the other

;

but if it be a vessel of melted platinum the very

greatest care must be used, because the sub-

stance is twice as heavy; yet no injury has

been done to any of the workmen in this op-

eration.

214 VAPORS OF METALS.

I have said that Deville depends upon intense

heat for carrying off vapor, and this brings meto the point of showing how vapors are carried

off. Here is a basin of mercury, which boils

easily, as you know, and gives us the oppor-

tunity of observing the facts and principles

which are to guide us. I have here two poles

of the battery, and if I bring them into contact

with the mercury, see what a development of

vapor we have! The mercury is flying off

rapidly, and I might, if I pleased, put all the

company around me in a bath of mercury-

vapor. And so, if we take this piece of lead

and treat it in the same way, it will also give

off vapor. Observe the fumes that rise from

it ; and even if it was so far inclosed from the

air that you could not form any litharge, you

would still have those abundant fumes flying

off. I may also take a piece of gold, and show

you the same thing. I have here a piece of

gold which I put upon a clean surface of Paris

limestone. Applying the heat of the blowpipe

to it, you see how the heat drives off the vapor

;

and if you notice at the end of the lecture, you

will observe on the stone a purple patch of

VAPORS OF LEAD AND GOLD. 215

condensed gold. Thus you see a proof of tlie

volatilization of gold. It is the same with sil-

ver. You will not be startled if I sometimes

use one agent and sometimes another to illus-

trate a particular point : the volatility of gold

or silver is the same thing, whether it be ef-

fected by the voltaic battery or by the blow-

pipe. [A lump of silver was placed in a char-

coal crucible between the poles of a voltaic

battery.] Now look at the fumes of silver,

and observe the peculiar and beautiful green

color which they produce. We shall now

show you this same process of boiling the sil-

ver, cast on a screen from the electric lamp

which you have before you; and while Dr.

Tyndall is kindly getting the lamp ready for

this purpose, let me tell you that Deville pro-

poses to throw out in this way all these extra-

neous things tbat I have spoken of, except two,

namely, iridium and rhodium. It so happens,

as he says, that iridium and rhodium do make

the metal more capable of resisting the attacks

of acids than platinum itself. Alloys are com-

pounded up to 25 per cent, ofrhodium and irid-

ium, by which the chemical inaction of the

216 VOLATILITY OF SILVER.

platinum is increased, and also its malleability

and other physical properties. [The image of

the voltaic discharge through vapor of silver

was now thrown upon the screen.] What you

have now on the screen is an inverted image

of what you saw when we heated the silver

before. The fine stream that you see around

the silver is the discharge of the electric force

that takes place, giving you that glorious green

light which you see in the ray ; and if Dr. Tyn-

dall will open the top of the lamp, you will see

the quantity of fumes that will come out of the

aperture, showing you at once the volatility of

silver.

I have now finished this imperfect account.

It is but an apology for not having brought the

process itself before you. I have done the best

I could under the circumstances, and I know

your kindness well, for if I were not aware

that I might trust to it, I would not appear

here so often as I have done. The gradual loss

of memory and of my other faculties is making

itself painfully evident to me, and requires,

every time I appear before you, the continued

remembrance of your kindness to enable me to

CONCLUSION. 217

get through my task. If I should happen to

go on too long, or should fail in doing what you

might desire, remember it is yourselves who are

chargeable by wishing me to remain. I have

desired to retire, as I think every man ought to

do before his faculties become impaired ; but I

must confess that the affection I have for this

place, and for those who frequent this place, is

such that I hardly know when the proper time

has arrived.

NOTES.

(1) Page 12. The Royal George sunk at Spit-

head on the 29th of August, 1782. Colonel Pas-

ley commenced operations for the removal of the

wreck by the explosion of gunpowder, in August,

1839. The candle which Professor Faraday ex-

hibited must therefore have been exposed to the

action of salt water for upward offifty-seven years.

(2) Page 13. The fat or tallow consists of a

chemical combination of fatty acids with glycerin.

The lime unites Avith the palmitic, oleic, and stear-

ic acids, and separates the glycerin. After wash-

ing, the insoluble lime soap is decomposed with

hot dilute sulphuric acid. The melted fatty acids

thus rise as an oil to the surface, when they are

decanted. They are again washed and cast into

thin plates, which, when cold, are placed betweenlayers of cocoanut matting and submitted to in-

tense hydraulic pressure. In this way the soft

oleic acid is squeezed out, while the hard palmitic

and stearic acids remain. These are farther puri-

fied by pressure at a higher temperature andwashing in warm dilute sulphuric acid, when they

are ready to be made into candles. These acids

220 NOTES.

are harder and whiter than the fats from whichthey were obtained, while at the same time they

are cleaner and more combustible.

(3) Page 15. A little borax or phosphorus salt is

sometimes added in order to make the ash fusible.

(*) Page 23. Capillary attraction or repulsion

is the cause which determines the ascent or de-

scent of a fluid in a capillary tube. If a piece of

thermometer tubing, open at each end, be plunged

into water, the latter Avill instantly rise in the tube

considerably above its external level. If, on the

other hand, the tube be plunged into mercury, a

repulsion instead of attraction will be exhibited,

and the level of the mercury will be lower in the

tube than it is outside.

(^) Page 25. The late Duke of Sussex was,

we believe, the first to show that a i^rawn might

be washed upon this principle. If the tail, after

pulling off the fan part, be placed in a tumbler of

water, and the head be allowed to hang over the

outside, the water will be sucked up the tail bycapillary attraction, and will continue to run out

through the head until the water in the glass has

sunk so low that the tail ceases to dip into it.

(^) Page 33. The alcohol had chloride of coi>

per dissolved in it : this produces a beautiful

crreen flame.

NOTES. 221

C^)Page 50. Lycopodium is a yellowish pow-

der found ill the fruit of the club moss {Lycopo-

dium clavatum). It is used in fire-works.

(®) Page 54. Bunsen has calculated that the

temperature of the oxyhydrogen blowpipe is

8061° Centigrade. Hydrogen burning in air has

a temperature of 3259° C, and coal-gas in air,

2350° C.

(^) Page 56. The following is the action of

the sulphuric in inflaming the mixture of sulphu-

ret of antimony and chlorate of potassa. A por-

tion of the latter is decomposed by the sulphuric

acid into oxide of chlorine, bisulphate of potassa,

and perchlorate of potassa. The oxide of chlo-

rine inflames the sulphuret of antimony, which is

a combustible body, and the whole mass instant-

ly bursts into flame.

(10) Page 59. The "air-burner," which is of

such value in the laboratory, owes its advantage

to this principle. It consists of a cylindrical met-

al chimney, covered at the top with a piece of

rather coarse iron wire gauze. This is support-

ed over an Argand burner in such a manner that

the gas may mix in the chimney with an amount

of air sufficient to burn the carbon and hydrogen

simultaneously, so that there may be no separa-

tion of carbon in the flame with consequent dep-

222 NOTES.

osition of soot. The flame, being unable to pass

through the wire gauze, burns in a steady, nearly-

invisible manner above.

(") Page 70. Water is in its densest state at

a temperature of 39*1° Fahrenheit.

(12) Page 70. A mixture of salt and pounded

ice reduces the temperature from 32° F. to zero,

the ice at the same time becoming fluid.

('3) Page 77. Potassium, the metallic basis of

potash, was discovered by Sir Humphrey Davy in

1807, who succeeded in separating it from potash

by means of a powerful voltaic battery. Its great

aflinity for oxygen causes it to decompose water

with evolution of hydrogen, which takes fire with

the heat produced.

(14) Page 93. Professor Faraday has calcula-

ted that there is as much electricity required to

decompose one grain of water as there is in a

very powerful flash of lightning.

(^^) Page 96. A solution of acetate of lead

submitted to the action of the voltaic current

yields lead at the negative pole, and brown per-

oxide of lead at the positive pole. A solution of

nitrate of silver, under the same circumstances,

yields silver at the negative pole, and peroxide

of silver at the ])ositive pole.

NOTES. 223

(iG) Page 123. The gas which is thus employ-

ed as a test for the presence ofoxygen is the bin-

oxide of nitrogen, or nitrous oxide. It is a color-

less gas, which, when brought in contact with ox-

ygen, unites with it, forming hyponitric acid, the

red gas referred to.

(^^) Page 146. 3Iarhle is a compound of car-

bonic acid and lime. The muriatic acid, being

the stronger of the two, takes the place of the car-

bonic acid, Avliich escapes as a gas, the residue

forming muriate of lime or chloride of calcium.

(^^) Page 180. Lead pyrophorus is made by

heating dry tartrate oflead in a glass tube (closed

at one end, and drawn out to a fine point at the

other) until no more vapors are evolved. The

open end of the tube is then to be sealed before

the blowpipe. When the tube is broken and the

contents shaken out into the air, they burn with

a red flash.

(1^) Page 211. Water gas is formed by pass-

ing vapor of water over red-hot charcoal or coke.

It is a mixture of hydrogen and carbonic oxide,

each of which is an inflammable gas.

THE END.

BOSTON UNIVERSITY

i7n DimaIII3171